Move ApiLocalScope out of class ApiState into class Thread so that the API local handles and zone e…

runtime/vm/dart_api_impl.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 
 #include "platform/assert.h"
 #include "vm/class_finalizer.h"
@@ skipping 156 matching lines @@
 static bool GetNativeStringArgument(NativeArguments* arguments,
                                     int arg_index,
                                     Dart_Handle* str,
                                     void** peer) {
   ASSERT(peer != NULL);
   if (Api::StringGetPeerHelper(arguments, arg_index, peer)) {
     *str = NULL;
     return true;
   }
   Thread* thread = arguments->thread();
-  Isolate* isolate = thread->isolate();
-  ASSERT(isolate == Isolate::Current());
+  ASSERT(thread == Thread::Current());
   *peer = NULL;
   REUSABLE_OBJECT_HANDLESCOPE(thread);
   Object& obj = thread->ObjectHandle();
   obj = arguments->NativeArgAt(arg_index);
   if (RawObject::IsStringClassId(obj.GetClassId())) {
-    ASSERT(isolate->api_state() &&
-           isolate->api_state()->top_scope() != NULL);
-    *str = Api::NewHandle(isolate, obj.raw());
+    ASSERT(thread->api_top_scope() != NULL);
+    *str = Api::NewHandle(thread, obj.raw());
     return true;
   }
   if (obj.IsNull()) {
     *str = Api::Null();
     return true;
   }
   return false;
 }
 
 
@@ skipping 97 matching lines @@
   }
   const Instance& instance = Instance::Cast(obj);
   int field_count = instance.NumNativeFields();
   ASSERT(num_fields != field_count);
   return Api::NewError(
       "%s: expected %d 'num_fields' but was passed in %d.",
       current_func, field_count, num_fields);
 }
 
 
-Heap::Space SpaceForExternal(Isolate* isolate, intptr_t size) {
-  Heap* heap = isolate->heap();
+Heap::Space SpaceForExternal(Thread* thread, intptr_t size) {
+  Heap* heap = thread->heap();
   // If 'size' would be a significant fraction of new space, then use old.
   static const int kExtNewRatio = 16;
   if (size > (heap->CapacityInWords(Heap::kNew) * kWordSize) / kExtNewRatio) {
     return Heap::kOld;
   } else {
     return Heap::kNew;
   }
 }
 
 
@@ skipping 24 matching lines @@
   if (function.IsNull()) {
     return ApiError::New(String::Handle(String::New("")));
   }
   const Array& args = Array::Handle(Array::New(kNumArgs));
   args.SetAt(0, receiver);
   args.SetAt(1, argument);
   return DartEntry::InvokeFunction(function, args);
 }
 
 
-Dart_Handle Api::InitNewHandle(Isolate* isolate, RawObject* raw) {
-  LocalHandles* local_handles = Api::TopScope(isolate)->local_handles();
+Dart_Handle Api::InitNewHandle(Thread* thread, RawObject* raw) {
+  LocalHandles* local_handles = Api::TopScope(thread)->local_handles();
   ASSERT(local_handles != NULL);
   LocalHandle* ref = local_handles->AllocateHandle();
   ref->set_raw(raw);
   return ref->apiHandle();
 }
 
 
-Dart_Handle Api::NewHandle(Isolate* isolate, RawObject* raw) {
+Dart_Handle Api::NewHandle(Thread* thread, RawObject* raw) {
   if (raw == Object::null()) {
     return Null();
   }
   if (raw == Bool::True().raw()) {
     return True();
   }
   if (raw == Bool::False().raw()) {
     return False();
   }
-  return InitNewHandle(isolate, raw);
+  return InitNewHandle(thread, raw);
 }
 
 
 RawObject* Api::UnwrapHandle(Dart_Handle object) {
 #if defined(DEBUG)
-  ASSERT(Thread::Current()->IsMutatorThread());
-  Isolate* isolate = Isolate::Current();
-  ASSERT(isolate != NULL);
-  ApiState* state = isolate->api_state();
-  ASSERT(state != NULL);
+  Thread* thread = Thread::Current();
+  ASSERT(thread->IsMutatorThread());
+  ASSERT(thread->isolate() != NULL);
   ASSERT(!FLAG_verify_handles ||
-         state->IsValidLocalHandle(object) ||
+         thread->IsValidLocalHandle(object) ||
          Dart::IsReadOnlyApiHandle(object));
   ASSERT(FinalizablePersistentHandle::raw_offset() == 0 &&
          PersistentHandle::raw_offset() == 0 &&
          LocalHandle::raw_offset() == 0);
 #endif
   return (reinterpret_cast<LocalHandle*>(object))->raw();
 }
 
 
 #define DEFINE_UNWRAP(type)                                                    \
@@ skipping 24 matching lines @@
     const ReusableObjectHandleScope& reuse, Dart_Handle dart_handle) {
   Object& ref = reuse.Handle();
   ref = Api::UnwrapHandle(dart_handle);
   if (ref.IsInstance()) {
     return Instance::Cast(ref);
   }
   return Object::null_instance();
 }
 
 
-Dart_Handle Api::CheckAndFinalizePendingClasses(Isolate* isolate) {
+Dart_Handle Api::CheckAndFinalizePendingClasses(Thread* thread) {
+  Isolate* isolate = thread->isolate();
   if (!isolate->AllowClassFinalization()) {
     // Class finalization is blocked for the isolate. Do nothing.
     return Api::Success();
   }
   if (ClassFinalizer::ProcessPendingClasses()) {
     return Api::Success();
   }
   ASSERT(isolate->object_store()->sticky_error() != Object::null());
-  return Api::NewHandle(isolate, isolate->object_store()->sticky_error());
+  return Api::NewHandle(thread, isolate->object_store()->sticky_error());
 }
 
 
 Dart_Isolate Api::CastIsolate(Isolate* isolate) {
   return reinterpret_cast<Dart_Isolate>(isolate);
 }
 
 
 Dart_Handle Api::NewError(const char* format, ...) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
 
   va_list args;
   va_start(args, format);
   intptr_t len = OS::VSNPrint(NULL, 0, format, args);
   va_end(args);
 
   char* buffer = Z->Alloc<char>(len + 1);
   va_list args2;
   va_start(args2, format);
   OS::VSNPrint(buffer, (len + 1), format, args2);
   va_end(args2);
 
   const String& message = String::Handle(Z, String::New(buffer));
-  return Api::NewHandle(I, ApiError::New(message));
+  return Api::NewHandle(T, ApiError::New(message));
 }
 
 
 void Api::SetupAcquiredError(Isolate* isolate) {
   ASSERT(isolate != NULL);
   ApiState* state = isolate->api_state();
   ASSERT(state != NULL);
   state->SetupAcquiredError();
 }
 
 
 Dart_Handle Api::AcquiredError(Isolate* isolate) {
   ASSERT(isolate != NULL);
   ApiState* state = isolate->api_state();
   ASSERT(state != NULL);
   PersistentHandle* acquired_error_handle = state->AcquiredError();
   return reinterpret_cast<Dart_Handle>(acquired_error_handle);
 }
 
 
-ApiLocalScope* Api::TopScope(Isolate* isolate) {
-  ASSERT(isolate != NULL);
-  ApiState* state = isolate->api_state();
-  ASSERT(state != NULL);
-  ApiLocalScope* scope = state->top_scope();
+ApiLocalScope* Api::TopScope(Thread* thread) {
+  ASSERT(thread != NULL);
+  ApiLocalScope* scope = thread->api_top_scope();
   ASSERT(scope != NULL);
   return scope;
 }
 
 
 void Api::InitOnce() {
   ASSERT(api_native_key_ == OSThread::kUnsetThreadLocalKey);
   api_native_key_ = OSThread::CreateThreadLocal();
   ASSERT(api_native_key_ != OSThread::kUnsetThreadLocalKey);
 }
@@ skipping 246 matching lines @@
 }
 
 
 DART_EXPORT const char* Dart_GetError(Dart_Handle handle) {
   DARTSCOPE(Thread::Current());
   const Object& obj = Object::Handle(Z, Api::UnwrapHandle(handle));
   if (obj.IsError()) {
     const Error& error = Error::Cast(obj);
     const char* str = error.ToErrorCString();
     intptr_t len = strlen(str) + 1;
-    char* str_copy = Api::TopScope(I)->zone()->Alloc<char>(len);
+    char* str_copy = Api::TopScope(T)->zone()->Alloc<char>(len);
     strncpy(str_copy, str, len);
     // Strip a possible trailing '\n'.
     if ((len > 1) && (str_copy[len - 2] == '\n')) {
       str_copy[len - 2] = '\0';
     }
     return str_copy;
   } else {
     return "";
   }
 }
 
 
 DART_EXPORT bool Dart_ErrorHasException(Dart_Handle handle) {
   DARTSCOPE(Thread::Current());
   const Object& obj = Object::Handle(Z, Api::UnwrapHandle(handle));
   return obj.IsUnhandledException();
 }
 
 
 DART_EXPORT Dart_Handle Dart_ErrorGetException(Dart_Handle handle) {
   DARTSCOPE(Thread::Current());
   const Object& obj = Object::Handle(Z, Api::UnwrapHandle(handle));
   if (obj.IsUnhandledException()) {
     const UnhandledException& error = UnhandledException::Cast(obj);
-    return Api::NewHandle(I, error.exception());
+    return Api::NewHandle(T, error.exception());
   } else if (obj.IsError()) {
     return Api::NewError("This error is not an unhandled exception error.");
   } else {
     return Api::NewError("Can only get exceptions from error handles.");
   }
 }
 
 
 DART_EXPORT Dart_Handle Dart_ErrorGetStacktrace(Dart_Handle handle) {
   DARTSCOPE(Thread::Current());
   const Object& obj = Object::Handle(Z, Api::UnwrapHandle(handle));
   if (obj.IsUnhandledException()) {
     const UnhandledException& error = UnhandledException::Cast(obj);
-    return Api::NewHandle(I, error.stacktrace());
+    return Api::NewHandle(T, error.stacktrace());
   } else if (obj.IsError()) {
     return Api::NewError("This error is not an unhandled exception error.");
   } else {
     return Api::NewError("Can only get stacktraces from error handles.");
   }
 }
 
 
 // TODO(turnidge): This clones Api::NewError.  I need to use va_copy to
 // fix this but not sure if it available on all of our builds.
 DART_EXPORT Dart_Handle Dart_NewApiError(const char* error) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
 
   const String& message = String::Handle(Z, String::New(error));
-  return Api::NewHandle(I, ApiError::New(message));
+  return Api::NewHandle(T, ApiError::New(message));
 }
 
 
 DART_EXPORT Dart_Handle Dart_NewUnhandledExceptionError(Dart_Handle exception) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
 
   Instance& obj = Instance::Handle(Z);
   intptr_t class_id = Api::ClassId(exception);
   if ((class_id == kApiErrorCid) || (class_id == kLanguageErrorCid)) {
     obj = String::New(::Dart_GetError(exception));
   } else {
     obj = Api::UnwrapInstanceHandle(Z, exception).raw();
     if (obj.IsNull()) {
       RETURN_TYPE_ERROR(Z, exception, Instance);
     }
   }
   const Stacktrace& stacktrace = Stacktrace::Handle(Z);
-  return Api::NewHandle(I, UnhandledException::New(obj, stacktrace));
+  return Api::NewHandle(T, UnhandledException::New(obj, stacktrace));
 }
 
 
 DART_EXPORT Dart_Handle Dart_PropagateError(Dart_Handle handle) {
   Thread* thread = Thread::Current();
-  Isolate* isolate = thread->isolate();
   {
     const Object& obj = Object::Handle(thread->zone(),
         Api::UnwrapHandle(handle));
     if (!obj.IsError()) {
       return Api::NewError(
           "%s expects argument 'handle' to be an error handle.  "
           "Did you forget to check Dart_IsError first?",
           CURRENT_FUNC);
     }
   }
   if (thread->top_exit_frame_info() == 0) {
     // There are no dart frames on the stack so it would be illegal to
     // propagate an error here.
     return Api::NewError("No Dart frames on stack, cannot propagate error.");
   }
 
   // Unwind all the API scopes till the exit frame before propagating.
-  ApiState* state = isolate->api_state();
-  ASSERT(state != NULL);
   const Error* error;
   {
     // We need to preserve the error object across the destruction of zones
     // when the ApiScopes are unwound.  By using NoSafepointScope, we can ensure
     // that GC won't touch the raw error object before creating a valid
     // handle for it in the surviving zone.
     NoSafepointScope no_safepoint;
     RawError* raw_error = Api::UnwrapErrorHandle(thread->zone(), handle).raw();
-    state->UnwindScopes(thread->top_exit_frame_info());
+    thread->UnwindScopes(thread->top_exit_frame_info());
     // Note that thread's zone is different here than at the beginning of this
     // function.
     error = &Error::Handle(thread->zone(), raw_error);
   }
   Exceptions::PropagateError(*error);
   UNREACHABLE();
   return Api::NewError("Cannot reach here.  Internal error.");
 }
 
 
 DART_EXPORT void _Dart_ReportErrorHandle(const char* file,
                                          int line,
                                          const char* handle,
                                          const char* message) {
   fprintf(stderr, "%s:%d: error handle: '%s':\n    '%s'\n",
           file, line, handle, message);
   OS::Abort();
 }
 
 
 DART_EXPORT Dart_Handle Dart_ToString(Dart_Handle object) {
   DARTSCOPE(Thread::Current());
   const Object& obj = Object::Handle(Z, Api::UnwrapHandle(object));
   if (obj.IsString()) {
-    return Api::NewHandle(I, obj.raw());
+    return Api::NewHandle(T, obj.raw());
   } else if (obj.IsInstance()) {
     CHECK_CALLBACK_STATE(T);
     const Instance& receiver = Instance::Cast(obj);
-    return Api::NewHandle(I, DartLibraryCalls::ToString(receiver));
+    return Api::NewHandle(T, DartLibraryCalls::ToString(receiver));
   } else {
     CHECK_CALLBACK_STATE(T);
     // This is a VM internal object. Call the C++ method of printing.
-    return Api::NewHandle(I, String::New(obj.ToCString()));
+    return Api::NewHandle(T, String::New(obj.ToCString()));
   }
 }
 
 
 DART_EXPORT bool Dart_IdentityEquals(Dart_Handle obj1, Dart_Handle obj2) {
   DARTSCOPE(Thread::Current());
   {
     NoSafepointScope no_safepoint_scope;
     if (Api::UnwrapHandle(obj1) == Api::UnwrapHandle(obj2)) {
       return true;
@@ skipping 45 matching lines @@
     if (bigint.FitsIntoUint64()) {
       return bigint.AsUint64Value();
     }
   }
   return 0;
 }
 
 
 DART_EXPORT Dart_Handle Dart_HandleFromPersistent(
     Dart_PersistentHandle object) {
-  Isolate* isolate = Isolate::Current();
+  Thread* thread = Thread::Current();
+  Isolate* isolate = thread->isolate();
   CHECK_ISOLATE(isolate);
   ApiState* state = isolate->api_state();
   ASSERT(state != NULL);
   PersistentHandle* ref = PersistentHandle::Cast(object);
-  return Api::NewHandle(isolate, ref->raw());
+  return Api::NewHandle(thread, ref->raw());
 }
 
 
 DART_EXPORT Dart_Handle Dart_HandleFromWeakPersistent(
     Dart_WeakPersistentHandle object) {
-  Isolate* isolate = Isolate::Current();
+  Thread* thread = Thread::Current();
+  Isolate* isolate = thread->isolate();
   CHECK_ISOLATE(isolate);
   ApiState* state = isolate->api_state();
   ASSERT(state != NULL);
   FinalizablePersistentHandle* weak_ref =
       FinalizablePersistentHandle::Cast(object);
-  return Api::NewHandle(isolate, weak_ref->raw());
+  return Api::NewHandle(thread, weak_ref->raw());
 }
 
 
 DART_EXPORT Dart_PersistentHandle Dart_NewPersistentHandle(Dart_Handle object) {
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   ApiState* state = I->api_state();
   ASSERT(state != NULL);
   const Object& old_ref = Object::Handle(Z, Api::UnwrapHandle(object));
   PersistentHandle* new_ref = state->persistent_handles().AllocateHandle();
   new_ref->set_raw(old_ref);
   return new_ref->apiHandle();
 }
 
 
 DART_EXPORT void Dart_SetPersistentHandle(Dart_PersistentHandle obj1,
                                           Dart_Handle obj2) {
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   ApiState* state = I->api_state();
   ASSERT(state != NULL);
   ASSERT(state->IsValidPersistentHandle(obj1));
   const Object& obj2_ref = Object::Handle(Z, Api::UnwrapHandle(obj2));
   PersistentHandle* obj1_ref = PersistentHandle::Cast(obj1);
   obj1_ref->set_raw(obj2_ref);
 }
 
 
 static Dart_WeakPersistentHandle AllocateFinalizableHandle(
@@ skipping 277 matching lines @@
     FATAL1("%s expects argument 'isolate' to be non-null.",  CURRENT_FUNC);
   }
   // TODO(16615): Validate isolate parameter.
   Isolate* iso = reinterpret_cast<Isolate*>(isolate);
   return iso->init_callback_data();
 }
 
 
 DART_EXPORT Dart_Handle Dart_DebugName() {
   DARTSCOPE(Thread::Current());
-  return Api::NewHandle(I, String::New(I->name()));
+  Isolate* I = T->isolate();
+  return Api::NewHandle(T, String::New(I->name()));
 }
 
 
 
 DART_EXPORT void Dart_EnterIsolate(Dart_Isolate isolate) {
   CHECK_NO_ISOLATE(Isolate::Current());
   // TODO(16615): Validate isolate parameter.
   Isolate* iso = reinterpret_cast<Isolate*>(isolate);
   if (iso->HasMutatorThread()) {
     FATAL("Multiple mutators within one isolate is not supported.");
@@ skipping 39 matching lines @@
         "%s expects that the value is set to true only.", CURRENT_FUNC);
   }
   Isolate::Current()->set_strict_compilation();
   return Api::Null();
 }
 
 
 static uint8_t* ApiReallocate(uint8_t* ptr,
                               intptr_t old_size,
                               intptr_t new_size) {
-  return Api::TopScope(Isolate::Current())->zone()->Realloc<uint8_t>(
+  return Api::TopScope(Thread::Current())->zone()->Realloc<uint8_t>(
       ptr, old_size, new_size);
 }
 
 
 DART_EXPORT Dart_Handle Dart_CreateSnapshot(
     uint8_t** vm_isolate_snapshot_buffer,
     intptr_t* vm_isolate_snapshot_size,
     uint8_t** isolate_snapshot_buffer,
     intptr_t* isolate_snapshot_size) {
   ASSERT(FLAG_load_deferred_eagerly);
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   if (vm_isolate_snapshot_buffer != NULL &&
       vm_isolate_snapshot_size == NULL) {
     RETURN_NULL_ERROR(vm_isolate_snapshot_size);
   }
   if (isolate_snapshot_buffer == NULL) {
     RETURN_NULL_ERROR(isolate_snapshot_buffer);
   }
   if (isolate_snapshot_size == NULL) {
     RETURN_NULL_ERROR(isolate_snapshot_size);
   }
   // Finalize all classes if needed.
-  Dart_Handle state = Api::CheckAndFinalizePendingClasses(I);
+  Dart_Handle state = Api::CheckAndFinalizePendingClasses(T);
   if (::Dart_IsError(state)) {
     return state;
   }
   I->heap()->CollectAllGarbage();
 #if defined(DEBUG)
   FunctionVisitor check_canonical(T);
   I->heap()->IterateObjects(&check_canonical);
 #endif  // #if defined(DEBUG).
 
   // Since this is only a snapshot the root library should not be set.
   I->object_store()->set_root_library(Library::Handle(Z));
   FullSnapshotWriter writer(vm_isolate_snapshot_buffer,
                             isolate_snapshot_buffer,
                             NULL, /* instructions_snapshot_buffer */
                             ApiReallocate,
                             false, /* snapshot_code */
                             true /* vm_isolate_is_symbolic */);
   writer.WriteFullSnapshot();
   *vm_isolate_snapshot_size = writer.VmIsolateSnapshotSize();
   *isolate_snapshot_size = writer.IsolateSnapshotSize();
   return Api::Success();
 }
 
 
 static Dart_Handle createLibrarySnapshot(Dart_Handle library,
                                          uint8_t** buffer,
                                          intptr_t* size) {
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   if (buffer == NULL) {
     RETURN_NULL_ERROR(buffer);
   }
   if (size == NULL) {
     RETURN_NULL_ERROR(size);
   }
   // Finalize all classes if needed.
-  Dart_Handle state = Api::CheckAndFinalizePendingClasses(I);
+  Dart_Handle state = Api::CheckAndFinalizePendingClasses(T);
   if (::Dart_IsError(state)) {
     return state;
   }
   Library& lib = Library::Handle(Z);
   if (library == Dart_Null()) {
     lib ^= I->object_store()->root_library();
   } else {
     lib ^= Api::UnwrapHandle(library);
   }
   I->heap()->CollectAllGarbage();
@@ skipping 68 matching lines @@
   ASSERT(data->monitor != NULL);
   MonitorLocker ml(data->monitor);
   data->done = true;
   ml.Notify();
 }
 
 
 DART_EXPORT Dart_Handle Dart_RunLoop() {
   Thread* T = Thread::Current();
   Isolate* I = T->isolate();
-  CHECK_ISOLATE_SCOPE(I);
+  CHECK_API_SCOPE(T);
   CHECK_CALLBACK_STATE(T);
   Monitor monitor;
   MonitorLocker ml(&monitor);
   {
     // The message handler run loop does not expect to have a current isolate
     // so we exit the isolate here and enter it again after the runloop is done.
     Thread::ExitIsolate();
     RunLoopData data;
     data.monitor = &monitor;
     data.done = false;
     I->message_handler()->Run(
         Dart::thread_pool(),
         NULL, RunLoopDone, reinterpret_cast<uword>(&data));
     while (!data.done) {
       ml.Wait();
     }
     Thread::EnterIsolate(I);
   }
   if (I->object_store()->sticky_error() != Object::null()) {
-    Dart_Handle error = Api::NewHandle(I, I->object_store()->sticky_error());
+    Dart_Handle error = Api::NewHandle(T, I->object_store()->sticky_error());
     I->object_store()->clear_sticky_error();
     return error;
   }
   if (FLAG_print_class_table) {
     HANDLESCOPE(T);
     I->class_table()->Print();
   }
   return Api::Success();
 }
 
 
 DART_EXPORT Dart_Handle Dart_HandleMessage() {
-  Thread* thread = Thread::Current();
-  Isolate* isolate = thread->isolate();
-  CHECK_ISOLATE_SCOPE(isolate);
-  CHECK_CALLBACK_STATE(thread);
-  if (isolate->message_handler()->HandleNextMessage() != MessageHandler::kOK) {
-    Dart_Handle error = Api::NewHandle(isolate,
-                                       isolate->object_store()->sticky_error());
-    isolate->object_store()->clear_sticky_error();
+  Thread* T = Thread::Current();
+  Isolate* I = T->isolate();
+  CHECK_API_SCOPE(T);
+  CHECK_CALLBACK_STATE(T);
+  if (I->message_handler()->HandleNextMessage() != MessageHandler::kOK) {
+    Dart_Handle error = Api::NewHandle(T,
+                                       I->object_store()->sticky_error());
+    I->object_store()->clear_sticky_error();
     return error;
   }
   return Api::Success();
 }
 
 
 DART_EXPORT bool Dart_HandleServiceMessages() {
-  Thread* thread = Thread::Current();
-  Isolate* isolate = thread->isolate();
-  CHECK_ISOLATE_SCOPE(isolate);
-  CHECK_CALLBACK_STATE(thread);
+  Thread* T = Thread::Current();
+  Isolate* I = T->isolate();
+  CHECK_API_SCOPE(T);
+  CHECK_CALLBACK_STATE(T);
 
-  ASSERT(isolate->GetAndClearResumeRequest() == false);
+  ASSERT(I->GetAndClearResumeRequest() == false);
   MessageHandler::MessageStatus status =
-      isolate->message_handler()->HandleOOBMessages();
-  bool resume = isolate->GetAndClearResumeRequest();
+      I->message_handler()->HandleOOBMessages();
+  bool resume = I->GetAndClearResumeRequest();
   return (status != MessageHandler::kOK) || resume;
 }
 
 
 DART_EXPORT bool Dart_HasServiceMessages() {
   Isolate* isolate = Isolate::Current();
   ASSERT(isolate);
   return isolate->message_handler()->HasOOBMessages();
 }
 
@@ skipping 27 matching lines @@
 
 
 DART_EXPORT Dart_Handle Dart_NewSendPort(Dart_Port port_id) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
   if (port_id == ILLEGAL_PORT) {
     return Api::NewError("%s: illegal port_id %" Pd64 ".",
                          CURRENT_FUNC,
                          port_id);
   }
-  return Api::NewHandle(I, SendPort::New(port_id));
+  return Api::NewHandle(T, SendPort::New(port_id));
 }
 
 
 DART_EXPORT Dart_Handle Dart_SendPortGetId(Dart_Handle port,
                                            Dart_Port* port_id) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
   const SendPort& send_port = Api::UnwrapSendPortHandle(Z, port);
   if (send_port.IsNull()) {
     RETURN_TYPE_ERROR(Z, port, SendPort);
@@ skipping 12 matching lines @@
   return isolate->main_port();
 }
 
 
 // --- Scopes ----
 
 DART_EXPORT void Dart_EnterScope() {
   Thread* thread = Thread::Current();
   Isolate* isolate = thread->isolate();
   CHECK_ISOLATE(isolate);
-  ApiState* state = isolate->api_state();
-  ASSERT(state != NULL);
-  ApiLocalScope* new_scope = state->reusable_scope();
+  ApiLocalScope* new_scope = thread->api_reusable_scope();
   if (new_scope == NULL) {
-    new_scope = new ApiLocalScope(state->top_scope(),
+    new_scope = new ApiLocalScope(thread->api_top_scope(),
                                   thread->top_exit_frame_info());
     ASSERT(new_scope != NULL);
   } else {
     new_scope->Reinit(thread,
-                      state->top_scope(),
+                      thread->api_top_scope(),
                       thread->top_exit_frame_info());
-    state->set_reusable_scope(NULL);
+    thread->set_api_reusable_scope(NULL);
   }
-  state->set_top_scope(new_scope);  // New scope is now the top scope.
+  thread->set_api_top_scope(new_scope);  // New scope is now the top scope.
 }
 
 
 DART_EXPORT void Dart_ExitScope() {
-  Thread* thread = Thread::Current();
-  Isolate* isolate = thread->isolate();
-  CHECK_ISOLATE_SCOPE(isolate);
-  ApiState* state = isolate->api_state();
-  ApiLocalScope* scope = state->top_scope();
-  ApiLocalScope* reusable_scope = state->reusable_scope();
-  state->set_top_scope(scope->previous());  // Reset top scope to previous.
+  Thread* T = Thread::Current();
+  CHECK_API_SCOPE(T);
+  ApiLocalScope* scope = T->api_top_scope();
+  ApiLocalScope* reusable_scope = T->api_reusable_scope();
+  T->set_api_top_scope(scope->previous());  // Reset top scope to previous.
   if (reusable_scope == NULL) {
-    scope->Reset(thread);  // Reset the old scope which we just exited.
-    state->set_reusable_scope(scope);
+    scope->Reset(T);  // Reset the old scope which we just exited.
+    T->set_api_reusable_scope(scope);
   } else {
     ASSERT(reusable_scope != scope);
     delete scope;
   }
 }
 
 
 DART_EXPORT uint8_t* Dart_ScopeAllocate(intptr_t size) {
   Zone* zone;
-  Isolate* isolate = Isolate::Current();
-  if (isolate != NULL) {
-    ApiState* state = isolate->api_state();
-    if (state == NULL) return NULL;
-    ApiLocalScope* scope = state->top_scope();
+  Thread* thread = Thread::Current();
+  if (thread != NULL) {
+    ApiLocalScope* scope = thread->api_top_scope();
     zone = scope->zone();
   } else {
     ApiNativeScope* scope = ApiNativeScope::Current();
     if (scope == NULL) return NULL;
     zone = scope->zone();
   }
   return reinterpret_cast<uint8_t*>(zone->AllocUnsafe(size));
 }
 
 
@@ skipping 23 matching lines @@
   const Instance& expected =
       Instance::CheckedHandle(Z, Api::UnwrapHandle(obj1));
   const Instance& actual =
       Instance::CheckedHandle(Z, Api::UnwrapHandle(obj2));
   const Object& result =
       Object::Handle(Z, DartLibraryCalls::Equals(expected, actual));
   if (result.IsBool()) {
     *value = Bool::Cast(result).value();
     return Api::Success();
   } else if (result.IsError()) {
-    return Api::NewHandle(I, result.raw());
+    return Api::NewHandle(T, result.raw());
   } else {
     return Api::NewError("Expected boolean result from ==");
   }
 }
 
 
 // TODO(iposva): This call actually implements IsInstanceOfClass.
 // Do we also need a real Dart_IsInstanceOf, which should take an instance
 // rather than an object?
 DART_EXPORT Dart_Handle Dart_ObjectIsType(Dart_Handle object,
@@ skipping 154 matching lines @@
 
 DART_EXPORT bool Dart_IsByteBuffer(Dart_Handle handle) {
   TRACE_API_CALL(CURRENT_FUNC);
   return Api::ClassId(handle) == kByteBufferCid;
 }
 
 
 DART_EXPORT bool Dart_IsFuture(Dart_Handle handle) {
   TRACE_API_CALL(CURRENT_FUNC);
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   const Object& obj = Object::Handle(Z, Api::UnwrapHandle(handle));
   if (obj.IsInstance()) {
     const Class& future_class =
         Class::Handle(I->object_store()->future_class());
     ASSERT(!future_class.IsNull());
     const Class& obj_class = Class::Handle(Z, obj.clazz());
     Error& malformed_type_error = Error::Handle(Z);
     bool is_future = obj_class.IsSubtypeOf(Object::null_type_arguments(),
                                            future_class,
                                            Object::null_type_arguments(),
                                            &malformed_type_error);
     ASSERT(malformed_type_error.IsNull());  // Type is a raw Future.
     return is_future;
   }
   return false;
 }
 
 
 // --- Instances ----
 
 DART_EXPORT Dart_Handle Dart_InstanceGetType(Dart_Handle instance) {
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   const Object& obj = Object::Handle(Z, Api::UnwrapHandle(instance));
   if (obj.IsNull()) {
-    return Api::NewHandle(I, I->object_store()->null_type());
+    return Api::NewHandle(T, I->object_store()->null_type());
   }
   if (!obj.IsInstance()) {
     RETURN_TYPE_ERROR(Z, instance, Instance);
   }
   const Type& type = Type::Handle(Instance::Cast(obj).GetType());
-  return Api::NewHandle(I, type.Canonicalize());
+  return Api::NewHandle(T, type.Canonicalize());
 }
 
 
 // --- Numbers, Integers and Doubles ----
 
 DART_EXPORT Dart_Handle Dart_IntegerFitsIntoInt64(Dart_Handle integer,
                                                   bool* fits) {
   // Fast path for Smis and Mints.
   Thread* thread = Thread::Current();
   Isolate* isolate = thread->isolate();
@@ skipping 41 matching lines @@
 }
 
 
 DART_EXPORT Dart_Handle Dart_NewInteger(int64_t value) {
   // Fast path for Smis.
   Thread* thread = Thread::Current();
   Isolate* isolate = thread->isolate();
   CHECK_ISOLATE(isolate);
   if (Smi::IsValid(value)) {
     NOHANDLESCOPE(thread);
-    return Api::NewHandle(isolate, Smi::New(static_cast<intptr_t>(value)));
+    return Api::NewHandle(thread, Smi::New(static_cast<intptr_t>(value)));
   }
   // Slow path for Mints and Bigints.
   DARTSCOPE(thread);
   CHECK_CALLBACK_STATE(thread);
-  return Api::NewHandle(isolate, Integer::New(value));
+  return Api::NewHandle(thread, Integer::New(value));
 }
 
 
 DART_EXPORT Dart_Handle Dart_NewIntegerFromUint64(uint64_t value) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
-  return Api::NewHandle(I, Integer::NewFromUint64(value));
+  return Api::NewHandle(T, Integer::NewFromUint64(value));
 }
 
 
 DART_EXPORT Dart_Handle Dart_NewIntegerFromHexCString(const char* str) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
   const String& str_obj = String::Handle(Z, String::New(str));
-  return Api::NewHandle(I, Integer::New(str_obj));
+  return Api::NewHandle(T, Integer::New(str_obj));
 }
 
 
 DART_EXPORT Dart_Handle Dart_IntegerToInt64(Dart_Handle integer,
                                             int64_t* value) {
   // Fast path for Smis.
   Thread* thread = Thread::Current();
   Isolate* isolate = thread->isolate();
   CHECK_ISOLATE(isolate);
   if (Api::IsSmi(integer)) {
@@ skipping 52 matching lines @@
       *value = bigint.AsUint64Value();
       return Api::Success();
     }
   }
   return Api::NewError("%s: Integer %s cannot be represented as a uint64_t.",
                        CURRENT_FUNC, int_obj.ToCString());
 }
 
 
 static uword BigintAllocate(intptr_t size) {
-  return Api::TopScope(Isolate::Current())->zone()->AllocUnsafe(size);
+  return Api::TopScope(Thread::Current())->zone()->AllocUnsafe(size);
 }
 
 
 DART_EXPORT Dart_Handle Dart_IntegerToHexCString(Dart_Handle integer,
                                                  const char** value) {
   DARTSCOPE(Thread::Current());
   const Integer& int_obj = Api::UnwrapIntegerHandle(Z, integer);
   if (int_obj.IsNull()) {
     RETURN_TYPE_ERROR(Z, integer, Integer);
   }
   if (int_obj.IsSmi() || int_obj.IsMint()) {
     const Bigint& bigint = Bigint::Handle(Z,
         Bigint::NewFromInt64(int_obj.AsInt64Value()));
     *value = bigint.ToHexCString(BigintAllocate);
   } else {
     *value = Bigint::Cast(int_obj).ToHexCString(BigintAllocate);
   }
   return Api::Success();
 }
 
 
 DART_EXPORT Dart_Handle Dart_NewDouble(double value) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
-  return Api::NewHandle(I, Double::New(value));
+  return Api::NewHandle(T, Double::New(value));
 }
 
 
 DART_EXPORT Dart_Handle Dart_DoubleValue(Dart_Handle double_obj,
                                          double* value) {
   DARTSCOPE(Thread::Current());
   const Double& obj = Api::UnwrapDoubleHandle(Z, double_obj);
   if (obj.IsNull()) {
     RETURN_TYPE_ERROR(Z, double_obj, Double);
   }
@@ skipping 50 matching lines @@
   return Api::Success();
 }
 
 
 DART_EXPORT Dart_Handle Dart_NewStringFromCString(const char* str) {
   DARTSCOPE(Thread::Current());
   if (str == NULL) {
     RETURN_NULL_ERROR(str);
   }
   CHECK_CALLBACK_STATE(T);
-  return Api::NewHandle(I, String::New(str));
+  return Api::NewHandle(T, String::New(str));
 }
 
 
 DART_EXPORT Dart_Handle Dart_NewStringFromUTF8(const uint8_t* utf8_array,
                                                intptr_t length) {
   DARTSCOPE(Thread::Current());
   if (utf8_array == NULL && length != 0) {
     RETURN_NULL_ERROR(utf8_array);
   }
   CHECK_LENGTH(length, String::kMaxElements);
   if (!Utf8::IsValid(utf8_array, length)) {
     return Api::NewError("%s expects argument 'str' to be valid UTF-8.",
                          CURRENT_FUNC);
   }
   CHECK_CALLBACK_STATE(T);
-  return Api::NewHandle(I, String::FromUTF8(utf8_array, length));
+  return Api::NewHandle(T, String::FromUTF8(utf8_array, length));
 }
 
 
 DART_EXPORT Dart_Handle Dart_NewStringFromUTF16(const uint16_t* utf16_array,
                                                 intptr_t length) {
   DARTSCOPE(Thread::Current());
   if (utf16_array == NULL && length != 0) {
     RETURN_NULL_ERROR(utf16_array);
   }
   CHECK_LENGTH(length, String::kMaxElements);
   CHECK_CALLBACK_STATE(T);
-  return Api::NewHandle(I, String::FromUTF16(utf16_array, length));
+  return Api::NewHandle(T, String::FromUTF16(utf16_array, length));
 }
 
 
 DART_EXPORT Dart_Handle Dart_NewStringFromUTF32(const int32_t* utf32_array,
                                                 intptr_t length) {
   DARTSCOPE(Thread::Current());
   if (utf32_array == NULL && length != 0) {
     RETURN_NULL_ERROR(utf32_array);
   }
   CHECK_LENGTH(length, String::kMaxElements);
   CHECK_CALLBACK_STATE(T);
-  return Api::NewHandle(I, String::FromUTF32(utf32_array, length));
+  return Api::NewHandle(T, String::FromUTF32(utf32_array, length));
 }
 
 
 DART_EXPORT Dart_Handle Dart_NewExternalLatin1String(
     const uint8_t* latin1_array,
     intptr_t length,
     void* peer,
     Dart_PeerFinalizer cback) {
   DARTSCOPE(Thread::Current());
   if (latin1_array == NULL && length != 0) {
     RETURN_NULL_ERROR(latin1_array);
   }
   CHECK_LENGTH(length, String::kMaxElements);
   CHECK_CALLBACK_STATE(T);
-  return Api::NewHandle(I,
+  return Api::NewHandle(T,
                         String::NewExternal(latin1_array,
                                             length,
                                             peer,
                                             cback,
-                                            SpaceForExternal(I, length)));
+                                            SpaceForExternal(T, length)));
 }
 
 
 DART_EXPORT Dart_Handle Dart_NewExternalUTF16String(const uint16_t* utf16_array,
                                                     intptr_t length,
                                                     void* peer,
                                                     Dart_PeerFinalizer cback) {
   DARTSCOPE(Thread::Current());
   if (utf16_array == NULL && length != 0) {
     RETURN_NULL_ERROR(utf16_array);
   }
   CHECK_LENGTH(length, String::kMaxElements);
   CHECK_CALLBACK_STATE(T);
   intptr_t bytes = length * sizeof(*utf16_array);
-  return Api::NewHandle(I,
+  return Api::NewHandle(T,
                         String::NewExternal(utf16_array,
                                             length,
                                             peer,
                                             cback,
-                                            SpaceForExternal(I, bytes)));
+                                            SpaceForExternal(T, bytes)));
 }
 
 
 DART_EXPORT Dart_Handle Dart_StringToCString(Dart_Handle object,
                                              const char** cstr) {
   DARTSCOPE(Thread::Current());
   if (cstr == NULL) {
     RETURN_NULL_ERROR(cstr);
   }
   const String& str_obj = Api::UnwrapStringHandle(Z, object);
   if (str_obj.IsNull()) {
     RETURN_TYPE_ERROR(Z, object, String);
   }
   intptr_t string_length = Utf8::Length(str_obj);
-  char* res = Api::TopScope(I)->zone()->Alloc<char>(string_length + 1);
+  char* res = Api::TopScope(T)->zone()->Alloc<char>(string_length + 1);
   if (res == NULL) {
     return Api::NewError("Unable to allocate memory");
   }
   const char* string_value = str_obj.ToCString();
   memmove(res, string_value, string_length + 1);
   ASSERT(res[string_length] == '\0');
   *cstr = res;
   return Api::Success();
 }
 
 
 DART_EXPORT Dart_Handle Dart_StringToUTF8(Dart_Handle str,
                                           uint8_t** utf8_array,
                                           intptr_t* length) {
   DARTSCOPE(Thread::Current());
   if (utf8_array == NULL) {
     RETURN_NULL_ERROR(utf8_array);
   }
   if (length == NULL) {
     RETURN_NULL_ERROR(length);
   }
   const String& str_obj = Api::UnwrapStringHandle(Z, str);
   if (str_obj.IsNull()) {
     RETURN_TYPE_ERROR(Z, str, String);
   }
   intptr_t str_len = Utf8::Length(str_obj);
-  *utf8_array = Api::TopScope(I)->zone()->Alloc<uint8_t>(str_len);
+  *utf8_array = Api::TopScope(T)->zone()->Alloc<uint8_t>(str_len);
   if (*utf8_array == NULL) {
     return Api::NewError("Unable to allocate memory");
   }
   str_obj.ToUTF8(*utf8_array, str_len);
   *length = str_len;
   return Api::Success();
 }
 
 
 DART_EXPORT Dart_Handle Dart_StringToLatin1(Dart_Handle str,
@@ skipping 99 matching lines @@
       ASSERT(str_obj.IsTwoByteString());
       ASSERT(length >= (copy_len * str_obj.CharSize()));
       uint16_t* utf16_array = reinterpret_cast<uint16_t*>(array);
       for (intptr_t i = 0; i < copy_len; i++) {
         utf16_array[i] = str_obj.CharAt(i);
       }
       TwoByteString::SetPeer(str_obj, peer, cback);
     }
     return str;
   }
-  return Api::NewHandle(I, str_obj.MakeExternal(array, length, peer, cback));
+  return Api::NewHandle(T, str_obj.MakeExternal(array, length, peer, cback));
 }
 
 
 DART_EXPORT Dart_Handle Dart_StringGetProperties(Dart_Handle object,
                                                  intptr_t* char_size,
                                                  intptr_t* str_len,
                                                  void** peer) {
   Thread* thread = Thread::Current();
   CHECK_ISOLATE(thread->isolate());
   ReusableObjectHandleScope reused_obj_handle(thread);
@@ skipping 13 matching lines @@
   return Api::Success();
 }
 
 
 // --- Lists ---
 
 DART_EXPORT Dart_Handle Dart_NewList(intptr_t length) {
   DARTSCOPE(Thread::Current());
   CHECK_LENGTH(length, Array::kMaxElements);
   CHECK_CALLBACK_STATE(T);
-  return Api::NewHandle(I, Array::New(length));
+  return Api::NewHandle(T, Array::New(length));
 }
 
 
 #define GET_LIST_LENGTH(zone, type, obj, len)                                  \
   type& array = type::Handle(zone);                                            \
   array ^= obj.raw();                                                          \
   *len = array.Length();                                                       \
   return Api::Success();                                                       \
 
 
@@ skipping 53 matching lines @@
       if (bigint.FitsIntoInt64()) {
         int64_t bigint_value = bigint.AsInt64Value();
         if (bigint_value >= kIntptrMin && bigint_value <= kIntptrMax) {
           *len = static_cast<intptr_t>(bigint_value);
         }
       }
     }
     return Api::NewError("Length of List object is greater than the "
                          "maximum value that 'len' parameter can hold");
   } else if (retval.IsError()) {
-    return Api::NewHandle(I, retval.raw());
+    return Api::NewHandle(T, retval.raw());
   } else {
     return Api::NewError("Length of List object is not an integer");
   }
 }
 
 
-#define GET_LIST_ELEMENT(isolate, type, obj, index)                            \
+#define GET_LIST_ELEMENT(thread, type, obj, index)                             \
   const type& array_obj = type::Cast(obj);                                     \
   if ((index >= 0) && (index < array_obj.Length())) {                          \
-    return Api::NewHandle(isolate, array_obj.At(index));                       \
+    return Api::NewHandle(thread, array_obj.At(index));                        \
   }                                                                            \
   return Api::NewError("Invalid index passed in to access list element");      \
 
 
 DART_EXPORT Dart_Handle Dart_ListGetAt(Dart_Handle list, intptr_t index) {
   DARTSCOPE(Thread::Current());
   const Object& obj = Object::Handle(Z, Api::UnwrapHandle(list));
   if (obj.IsArray()) {
-    GET_LIST_ELEMENT(I, Array, obj, index);
+    GET_LIST_ELEMENT(T, Array, obj, index);
   } else if (obj.IsGrowableObjectArray()) {
-    GET_LIST_ELEMENT(I, GrowableObjectArray, obj, index);
+    GET_LIST_ELEMENT(T, GrowableObjectArray, obj, index);
   } else if (obj.IsError()) {
     return list;
   } else {
     CHECK_CALLBACK_STATE(T);
     // Check and handle a dart object that implements the List interface.
     const Instance& instance = Instance::Handle(Z, GetListInstance(Z, obj));
     if (!instance.IsNull()) {
-      return Api::NewHandle(I, Send1Arg(
+      return Api::NewHandle(T, Send1Arg(
           instance,
           Symbols::IndexToken(),
           Instance::Handle(Z, Integer::New(index))));
     }
     return Api::NewError("Object does not implement the 'List' interface");
   }
 }
 
 
-#define GET_LIST_RANGE(isolate, type, obj, offset, length)                     \
+#define GET_LIST_RANGE(thread, type, obj, offset, length)                      \
   const type& array_obj = type::Cast(obj);                                     \
   if ((offset >= 0) && (offset + length <= array_obj.Length())) {              \
     for (intptr_t index = 0; index < length; ++index) {                        \
-      result[index] = Api::NewHandle(isolate, array_obj.At(index + offset));   \
+      result[index] = Api::NewHandle(thread, array_obj.At(index + offset));    \
     }                                                                          \
     return Api::Success();                                                     \
   }                                                                            \
   return Api::NewError("Invalid offset/length passed in to access list");      \
 
 
 DART_EXPORT Dart_Handle Dart_ListGetRange(Dart_Handle list,
                                           intptr_t offset,
                                           intptr_t length,
                                           Dart_Handle* result) {
   DARTSCOPE(Thread::Current());
   if (result == NULL) {
     RETURN_NULL_ERROR(result);
   }
   const Object& obj = Object::Handle(Z, Api::UnwrapHandle(list));
   if (obj.IsArray()) {
-    GET_LIST_RANGE(I, Array, obj, offset, length);
+    GET_LIST_RANGE(T, Array, obj, offset, length);
   } else if (obj.IsGrowableObjectArray()) {
-    GET_LIST_RANGE(I, GrowableObjectArray, obj, offset, length);
+    GET_LIST_RANGE(T, GrowableObjectArray, obj, offset, length);
   } else if (obj.IsError()) {
     return list;
   } else {
     CHECK_CALLBACK_STATE(T);
     // Check and handle a dart object that implements the List interface.
     const Instance& instance = Instance::Handle(Z, GetListInstance(Z, obj));
     if (!instance.IsNull()) {
       const intptr_t kNumArgs = 2;
       ArgumentsDescriptor args_desc(
           Array::Handle(ArgumentsDescriptor::New(kNumArgs)));
       const Function& function = Function::Handle(Z,
           Resolver::ResolveDynamic(instance,
                                    Symbols::AssignIndexToken(),
                                    args_desc));
       if (!function.IsNull()) {
         const Array& args = Array::Handle(Array::New(kNumArgs));
         args.SetAt(0, instance);
         Instance& index = Instance::Handle(Z);
         for (intptr_t i = 0; i < length; ++i) {
           index = Integer::New(i);
           args.SetAt(1, index);
-          Dart_Handle value = Api::NewHandle(I,
+          Dart_Handle value = Api::NewHandle(T,
               DartEntry::InvokeFunction(function, args));
           if (::Dart_IsError(value))
             return value;
           result[i] = value;
         }
         return Api::Success();
       }
     }
     return Api::NewError("Object does not implement the 'List' interface");
   }
@@ skipping 42 matching lines @@
       if (!function.IsNull()) {
         const Integer& index_obj = Integer::Handle(Z, Integer::New(index));
         const Object& value_obj = Object::Handle(Z, Api::UnwrapHandle(value));
         if (!value_obj.IsNull() && !value_obj.IsInstance()) {
           RETURN_TYPE_ERROR(Z, value, Instance);
         }
         const Array& args = Array::Handle(Z, Array::New(kNumArgs));
         args.SetAt(0, instance);
         args.SetAt(1, index_obj);
         args.SetAt(2, value_obj);
-        return Api::NewHandle(I, DartEntry::InvokeFunction(function,
-                                                                 args));
+        return Api::NewHandle(
+            T, DartEntry::InvokeFunction(function, args));
       }
     }
     return Api::NewError("Object does not implement the 'List' interface");
   }
 }
 
 
 static RawObject* ResolveConstructor(const char* current_func,
                                      const Class& cls,
                                      const String& class_name,
                                      const String& dotted_name,
                                      int num_args);
 
 
 static RawObject* ThrowArgumentError(const char* exception_message) {
   Thread* thread = Thread::Current();
-  Isolate* isolate = thread->isolate();
   Zone* zone = thread->zone();
   // Lookup the class ArgumentError in dart:core.
   const String& lib_url = String::Handle(String::New("dart:core"));
   const String& class_name = String::Handle(String::New("ArgumentError"));
   const Library& lib =
       Library::Handle(zone, Library::LookupLibrary(lib_url));
   if (lib.IsNull()) {
     const String& message = String::Handle(
         String::NewFormatted("%s: library '%s' not found.",
                              CURRENT_FUNC, lib_url.ToCString()));
@@ skipping 28 matching lines @@
 
   if (thread->top_exit_frame_info() == 0) {
     // There are no dart frames on the stack so it would be illegal to
     // throw an exception here.
     const String& message = String::Handle(
             String::New("No Dart frames on stack, cannot throw exception"));
     return ApiError::New(message);
   }
   // Unwind all the API scopes till the exit frame before throwing an
   // exception.
-  ApiState* state = isolate->api_state();
-  ASSERT(state != NULL);
   const Instance* saved_exception;
   {
     NoSafepointScope no_safepoint;
     RawInstance* raw_exception = exception.raw();
-    state->UnwindScopes(thread->top_exit_frame_info());
+    thread->UnwindScopes(thread->top_exit_frame_info());
     saved_exception = &Instance::Handle(raw_exception);
   }
   Exceptions::Throw(thread, *saved_exception);
   const String& message = String::Handle(
           String::New("Exception was not thrown, internal error"));
   return ApiError::New(message);
 }
 
 // TODO(sgjesse): value should always be smaller then 0xff. Add error handling.
 #define GET_LIST_ELEMENT_AS_BYTES(type, obj, native_array, offset, length)     \
   const type& array = type::Cast(obj);                                         \
   if (Utils::RangeCheck(offset, length, array.Length())) {                     \
     Object& element = Object::Handle(Z);                                       \
     for (int i = 0; i < length; i++) {                                         \
       element = array.At(offset + i);                                          \
       if (!element.IsInteger()) {                                              \
-        return Api::NewHandle(I,                                               \
+        return Api::NewHandle(T,                                               \
             ThrowArgumentError("List contains non-int elements"));             \
                                                                                \
       }                                                                        \
       const Integer& integer = Integer::Cast(element);                         \
       native_array[i] = static_cast<uint8_t>(integer.AsInt64Value() & 0xff);   \
       ASSERT(integer.AsInt64Value() <= 0xff);                                  \
     }                                                                          \
     return Api::Success();                                                     \
   }                                                                            \
   return Api::NewError("Invalid length passed in to access array elements");   \
@@ skipping 84 matching lines @@
       Object& result = Object::Handle(Z);
       Integer& intobj = Integer::Handle(Z);
       const Array& args = Array::Handle(Z, Array::New(kNumArgs));
       args.SetAt(0, instance);  // Set up the receiver as the first argument.
       for (int i = 0; i < length; i++) {
         HANDLESCOPE(T);
         intobj = Integer::New(offset + i);
         args.SetAt(1, intobj);
         result = DartEntry::InvokeFunction(function, args);
         if (result.IsError()) {
-          return Api::NewHandle(I, result.raw());
+          return Api::NewHandle(T, result.raw());
         }
         if (!result.IsInteger()) {
           return Api::NewError("%s expects the argument 'list' to be "
                                "a List of int", CURRENT_FUNC);
         }
         const Integer& integer_result = Integer::Cast(result);
         ASSERT(integer_result.AsInt64Value() <= 0xff);
         // TODO(hpayer): value should always be smaller then 0xff. Add error
         // handling.
         native_array[i] =
@@ skipping 68 matching lines @@
       const Array& args = Array::Handle(Z, Array::New(kNumArgs));
       args.SetAt(0, instance);  // Set up the receiver as the first argument.
       for (int i = 0; i < length; i++) {
         indexobj = Integer::New(offset + i);
         valueobj = Integer::New(native_array[i]);
         args.SetAt(1, indexobj);
         args.SetAt(2, valueobj);
         const Object& result = Object::Handle(Z,
             DartEntry::InvokeFunction(function, args));
         if (result.IsError()) {
-          return Api::NewHandle(I, result.raw());
+          return Api::NewHandle(T, result.raw());
         }
       }
       return Api::Success();
     }
   }
   return Api::NewError("Object does not implement the 'List' interface");
 }
 
 
 // --- Maps ---
 
 DART_EXPORT Dart_Handle Dart_MapGetAt(Dart_Handle map, Dart_Handle key) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
   const Object& obj = Object::Handle(Z, Api::UnwrapHandle(map));
   const Instance& instance = Instance::Handle(Z, GetMapInstance(Z, obj));
   if (!instance.IsNull()) {
     const Object& key_obj = Object::Handle(Api::UnwrapHandle(key));
     if (!(key_obj.IsInstance() || key_obj.IsNull())) {
       return Api::NewError("Key is not an instance");
     }
-    return Api::NewHandle(I,
+    return Api::NewHandle(T,
         Send1Arg(instance, Symbols::IndexToken(), Instance::Cast(key_obj)));
   }
   return Api::NewError("Object does not implement the 'Map' interface");
 }
 
 
 DART_EXPORT Dart_Handle Dart_MapContainsKey(Dart_Handle map, Dart_Handle key) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
   const Object& obj = Object::Handle(Z, Api::UnwrapHandle(map));
   const Instance& instance = Instance::Handle(Z, GetMapInstance(Z, obj));
   if (!instance.IsNull()) {
     const Object& key_obj = Object::Handle(Z, Api::UnwrapHandle(key));
     if (!(key_obj.IsInstance() || key_obj.IsNull())) {
       return Api::NewError("Key is not an instance");
     }
-    return Api::NewHandle(I, Send1Arg(
+    return Api::NewHandle(T, Send1Arg(
        instance,
        String::Handle(Z, String::New("containsKey")),
        Instance::Cast(key_obj)));
   }
   return Api::NewError("Object does not implement the 'Map' interface");
 }
 
 
 DART_EXPORT Dart_Handle Dart_MapKeys(Dart_Handle map) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
   Object& obj = Object::Handle(Z, Api::UnwrapHandle(map));
   Instance& instance = Instance::Handle(Z, GetMapInstance(Z, obj));
   if (!instance.IsNull()) {
     const Object& iterator = Object::Handle(Send0Arg(
         instance, String::Handle(Z, String::New("get:keys"))));
     if (!iterator.IsInstance()) {
-      return Api::NewHandle(I, iterator.raw());
+      return Api::NewHandle(T, iterator.raw());
     }
-    return Api::NewHandle(I, Send0Arg(
+    return Api::NewHandle(T, Send0Arg(
         Instance::Cast(iterator),
         String::Handle(String::New("toList"))));
   }
   return Api::NewError("Object does not implement the 'Map' interface");
 }
 
 
 // --- Typed Data ---
 
 // Helper method to get the type of a TypedData object.
@@ skipping 116 matching lines @@
   return ResolveConstructor(CURRENT_FUNC,
                             cls,
                             Symbols::ByteData(),
                             constructor_name,
                             num_args);
 }
 
 
 static Dart_Handle NewByteData(Thread* thread, intptr_t length) {
   CHECK_LENGTH(length, TypedData::MaxElements(kTypedDataInt8ArrayCid));
-  Isolate* isolate = thread->isolate();
   Zone* zone = thread->zone();
   Object& result = Object::Handle(zone);
   result = GetByteDataConstructor(thread, Symbols::ByteDataDot(), 1);
   ASSERT(!result.IsNull());
   ASSERT(result.IsFunction());
   const Function& factory = Function::Cast(result);
   ASSERT(!factory.IsGenerativeConstructor());
 
   // Create the argument list.
   const Array& args = Array::Handle(zone, Array::New(2));
   // Factories get type arguments.
   args.SetAt(0, Object::null_type_arguments());
   args.SetAt(1, Smi::Handle(zone, Smi::New(length)));
 
   // Invoke the constructor and return the new object.
   result = DartEntry::InvokeFunction(factory, args);
   ASSERT(result.IsInstance() || result.IsNull() || result.IsError());
-  return Api::NewHandle(isolate, result.raw());
+  return Api::NewHandle(thread, result.raw());
 }
 
 
-static Dart_Handle NewTypedData(Isolate* isolate,
+static Dart_Handle NewTypedData(Thread* thread,
                                 intptr_t cid,
                                 intptr_t length) {
   CHECK_LENGTH(length, TypedData::MaxElements(cid));
-  return Api::NewHandle(isolate, TypedData::New(cid, length));
+  return Api::NewHandle(thread, TypedData::New(cid, length));
 }
 
 
 static Dart_Handle NewExternalTypedData(
     Thread* thread, intptr_t cid, void* data, intptr_t length) {
   CHECK_LENGTH(length, ExternalTypedData::MaxElements(cid));
-  Isolate* isolate = thread->isolate();
   Zone* zone = thread->zone();
   intptr_t bytes = length * ExternalTypedData::ElementSizeInBytes(cid);
   const ExternalTypedData& result = ExternalTypedData::Handle(
       zone,
       ExternalTypedData::New(cid,
                              reinterpret_cast<uint8_t*>(data),
                              length,
-                             SpaceForExternal(isolate, bytes)));
-  return Api::NewHandle(isolate, result.raw());
+                             SpaceForExternal(thread, bytes)));
+  return Api::NewHandle(thread, result.raw());
 }
 
 
 static Dart_Handle NewExternalByteData(
     Thread* thread, void* data, intptr_t length) {
   Zone* zone = thread->zone();
-  Isolate* isolate = thread->isolate();
   Dart_Handle ext_data = NewExternalTypedData(
       thread, kExternalTypedDataUint8ArrayCid, data, length);
   if (::Dart_IsError(ext_data)) {
     return ext_data;
   }
   Object& result = Object::Handle(zone);
   result = GetByteDataConstructor(thread, Symbols::ByteDataDot_view(), 3);
   ASSERT(!result.IsNull());
   ASSERT(result.IsFunction());
   const Function& factory = Function::Cast(result);
   ASSERT(!factory.IsGenerativeConstructor());
 
   // Create the argument list.
   const intptr_t num_args = 3;
   const Array& args = Array::Handle(zone, Array::New(num_args + 1));
   // Factories get type arguments.
   args.SetAt(0, Object::null_type_arguments());
   const ExternalTypedData& array =
       Api::UnwrapExternalTypedDataHandle(zone, ext_data);
   args.SetAt(1, array);
   Smi& smi = Smi::Handle(zone);
   smi = Smi::New(0);
   args.SetAt(2, smi);
   smi = Smi::New(length);
   args.SetAt(3, smi);
 
   // Invoke the constructor and return the new object.
   result = DartEntry::InvokeFunction(factory, args);
   ASSERT(result.IsNull() || result.IsInstance() || result.IsError());
-  return Api::NewHandle(isolate, result.raw());
+  return Api::NewHandle(thread, result.raw());
 }
 
 
 DART_EXPORT Dart_Handle Dart_NewTypedData(Dart_TypedData_Type type,
                                           intptr_t length) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
   switch (type) {
     case Dart_TypedData_kByteData :
       return NewByteData(T, length);
     case Dart_TypedData_kInt8 :
-      return NewTypedData(I, kTypedDataInt8ArrayCid, length);
+      return NewTypedData(T, kTypedDataInt8ArrayCid, length);
     case Dart_TypedData_kUint8 :
-      return NewTypedData(I, kTypedDataUint8ArrayCid, length);
+      return NewTypedData(T, kTypedDataUint8ArrayCid, length);
     case Dart_TypedData_kUint8Clamped :
-      return NewTypedData(I, kTypedDataUint8ClampedArrayCid, length);
+      return NewTypedData(T, kTypedDataUint8ClampedArrayCid, length);
     case Dart_TypedData_kInt16 :
-      return NewTypedData(I, kTypedDataInt16ArrayCid, length);
+      return NewTypedData(T, kTypedDataInt16ArrayCid, length);
     case Dart_TypedData_kUint16 :
-      return NewTypedData(I, kTypedDataUint16ArrayCid, length);
+      return NewTypedData(T, kTypedDataUint16ArrayCid, length);
     case Dart_TypedData_kInt32 :
-      return NewTypedData(I, kTypedDataInt32ArrayCid, length);
+      return NewTypedData(T, kTypedDataInt32ArrayCid, length);
     case Dart_TypedData_kUint32 :
-      return NewTypedData(I, kTypedDataUint32ArrayCid, length);
+      return NewTypedData(T, kTypedDataUint32ArrayCid, length);
     case Dart_TypedData_kInt64 :
-      return NewTypedData(I, kTypedDataInt64ArrayCid, length);
+      return NewTypedData(T, kTypedDataInt64ArrayCid, length);
     case Dart_TypedData_kUint64 :
-      return NewTypedData(I, kTypedDataUint64ArrayCid, length);
+      return NewTypedData(T, kTypedDataUint64ArrayCid, length);
     case Dart_TypedData_kFloat32 :
-      return NewTypedData(I, kTypedDataFloat32ArrayCid,  length);
+      return NewTypedData(T, kTypedDataFloat32ArrayCid,  length);
     case Dart_TypedData_kFloat64 :
-      return NewTypedData(I, kTypedDataFloat64ArrayCid, length);
+      return NewTypedData(T, kTypedDataFloat64ArrayCid, length);
     case Dart_TypedData_kFloat32x4:
-      return NewTypedData(I, kTypedDataFloat32x4ArrayCid, length);
+      return NewTypedData(T, kTypedDataFloat32x4ArrayCid, length);
     default:
       return Api::NewError("%s expects argument 'type' to be of 'TypedData'",
                            CURRENT_FUNC);
   }
   UNREACHABLE();
   return Api::Null();
 }
 
 
 DART_EXPORT Dart_Handle Dart_NewExternalTypedData(
@@ skipping 92 matching lines @@
   // Create the argument list.
   const Array& args = Array::Handle(Z, Array::New(2));
   // Factories get type arguments.
   args.SetAt(0, Object::null_type_arguments());
   const Object& obj = Object::Handle(Z, Api::UnwrapHandle(typed_data));
   args.SetAt(1, obj);
 
   // Invoke the factory constructor and return the new object.
   result = DartEntry::InvokeFunction(factory, args);
   ASSERT(result.IsInstance() || result.IsNull() || result.IsError());
-  return Api::NewHandle(I, result.raw());
+  return Api::NewHandle(T, result.raw());
 }
 
 
 // Structure to record acquired typed data for verification purposes.
 class AcquiredData {
  public:
   AcquiredData(void* data, intptr_t size_in_bytes, bool copy)
       : size_in_bytes_(size_in_bytes), data_(data), data_copy_(NULL) {
     if (copy) {
       data_copy_ = malloc(size_in_bytes_);
@@ skipping 21 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(AcquiredData);
 };
 
 
 DART_EXPORT Dart_Handle Dart_TypedDataAcquireData(Dart_Handle object,
                                                   Dart_TypedData_Type* type,
                                                   void** data,
                                                   intptr_t* len) {
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   intptr_t class_id = Api::ClassId(object);
   if (!RawObject::IsExternalTypedDataClassId(class_id) &&
       !RawObject::IsTypedDataViewClassId(class_id) &&
       !RawObject::IsTypedDataClassId(class_id)) {
     RETURN_TYPE_ERROR(Z, object, 'TypedData');
   }
   if (type == NULL) {
     RETURN_NULL_ERROR(type);
   }
   if (data == NULL) {
@@ skipping 69 matching lines @@
     data_tmp = ad->GetData();
   }
   *data = data_tmp;
   *len = length;
   return Api::Success();
 }
 
 
 DART_EXPORT Dart_Handle Dart_TypedDataReleaseData(Dart_Handle object) {
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   intptr_t class_id = Api::ClassId(object);
   if (!RawObject::IsExternalTypedDataClassId(class_id) &&
       !RawObject::IsTypedDataViewClassId(class_id) &&
       !RawObject::IsTypedDataClassId(class_id)) {
     RETURN_TYPE_ERROR(Z, object, 'TypedData');
   }
   if (!RawObject::IsExternalTypedDataClassId(class_id)) {
     T->DecrementNoSafepointScopeDepth();
     END_NO_CALLBACK_SCOPE(T);
   }
@@ skipping 16 matching lines @@
   Thread* thread = Thread::Current();
   Zone* zone = thread->zone();
   Isolate* isolate = thread->isolate();
   CHECK_ISOLATE(isolate);
   intptr_t class_id = Api::ClassId(object);
   if (class_id != kByteBufferCid) {
     RETURN_TYPE_ERROR(zone, object, 'ByteBuffer');
   }
   const Instance& instance = Api::UnwrapInstanceHandle(zone, object);
   ASSERT(!instance.IsNull());
-  return Api::NewHandle(isolate, ByteBuffer::Data(instance));
+  return Api::NewHandle(thread, ByteBuffer::Data(instance));
 }
 
 
 // ---  Invoking Constructors, Methods, and Field accessors ---
 
 static RawObject* ResolveConstructor(const char* current_func,
                                      const Class& cls,
                                      const String& class_name,
                                      const String& constr_name,
                                      int num_args) {
@@ skipping 90 matching lines @@
 
   // Resolve the constructor.
   String& constr_name =
       String::Handle(String::Concat(base_constructor_name, dot_name));
   result = ResolveConstructor("Dart_New",
                               cls,
                               base_constructor_name,
                               constr_name,
                               number_of_arguments);
   if (result.IsError()) {
-    return Api::NewHandle(I, result.raw());
+    return Api::NewHandle(T, result.raw());
   }
   ASSERT(result.IsFunction());
   Function& constructor = Function::Handle(Z);
   constructor ^= result.raw();
 
   Instance& new_object = Instance::Handle(Z);
   if (constructor.IsRedirectingFactory()) {
     ClassFinalizer::ResolveRedirectingFactory(cls, constructor);
     Type& redirect_type = Type::Handle(constructor.RedirectionType());
     constructor = constructor.RedirectionTarget();
     if (constructor.IsNull()) {
       ASSERT(redirect_type.IsMalformed());
-      return Api::NewHandle(I, redirect_type.error());
+      return Api::NewHandle(T, redirect_type.error());
     }
 
     if (!redirect_type.IsInstantiated()) {
       // The type arguments of the redirection type are instantiated from the
       // type arguments of the type argument.
       Error& bound_error = Error::Handle();
       redirect_type ^= redirect_type.InstantiateFrom(type_arguments,
                                                      &bound_error);
       if (!bound_error.IsNull()) {
-        return Api::NewHandle(I, bound_error.raw());
+        return Api::NewHandle(T, bound_error.raw());
       }
       redirect_type ^= redirect_type.Canonicalize();
     }
 
     type_obj = redirect_type.raw();
     type_arguments = redirect_type.arguments();
 
     cls = type_obj.type_class();
   }
   if (constructor.IsGenerativeConstructor()) {
@@ skipping 18 matching lines @@
     args.SetAt(arg_index++, Smi::Handle(Z, Smi::New(Function::kCtorPhaseAll)));
   } else {
     // Factories get type arguments.
     args.SetAt(arg_index++, type_arguments);
   }
   Object& argument = Object::Handle(Z);
   for (int i = 0; i < number_of_arguments; i++) {
     argument = Api::UnwrapHandle(arguments[i]);
     if (!argument.IsNull() && !argument.IsInstance()) {
       if (argument.IsError()) {
-        return Api::NewHandle(I, argument.raw());
+        return Api::NewHandle(T, argument.raw());
       } else {
         return Api::NewError(
             "%s expects arguments[%d] to be an Instance handle.",
             CURRENT_FUNC, i);
       }
     }
     args.SetAt(arg_index++, argument);
   }
 
   // Invoke the constructor and return the new object.
   result = DartEntry::InvokeFunction(constructor, args);
   if (result.IsError()) {
-    return Api::NewHandle(I, result.raw());
+    return Api::NewHandle(T, result.raw());
   }
 
   if (constructor.IsGenerativeConstructor()) {
     ASSERT(result.IsNull());
   } else {
     ASSERT(result.IsNull() || result.IsInstance());
     new_object ^= result.raw();
   }
-  return Api::NewHandle(I, new_object.raw());
+  return Api::NewHandle(T, new_object.raw());
 }
 
 
 static RawInstance* AllocateObject(Thread* thread, const Class& cls) {
   if (!cls.is_fields_marked_nullable()) {
     // Mark all fields as nullable.
     Zone* zone = thread->zone();
     Class& iterate_cls = Class::Handle(zone, cls.raw());
     Field& field = Field::Handle(zone);
     Array& fields = Array::Handle(zone);
@@ skipping 28 matching lines @@
   }
   const Class& cls = Class::Handle(Z, type_obj.type_class());
 #if defined(DEBUG)
   if (!cls.is_allocated() && Dart::IsRunningPrecompiledCode()) {
     return Api::NewError("Precompilation dropped '%s'", cls.ToCString());
   }
 #endif
   const Error& error = Error::Handle(Z, cls.EnsureIsFinalized(T));
   if (!error.IsNull()) {
     // An error occurred, return error object.
-    return Api::NewHandle(I, error.raw());
+    return Api::NewHandle(T, error.raw());
   }
-  return Api::NewHandle(I, AllocateObject(T, cls));
+  return Api::NewHandle(T, AllocateObject(T, cls));
 }
 
 
 DART_EXPORT Dart_Handle Dart_AllocateWithNativeFields(
     Dart_Handle type,
     intptr_t num_native_fields,
     const intptr_t* native_fields) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
 
   const Type& type_obj = Api::UnwrapTypeHandle(Z, type);
   // Get the class to instantiate.
   if (type_obj.IsNull()) {
     RETURN_TYPE_ERROR(Z, type, Type);
   }
   if (native_fields == NULL) {
     RETURN_NULL_ERROR(native_fields);
   }
   const Class& cls = Class::Handle(Z, type_obj.type_class());
 #if defined(DEBUG)
   if (!cls.is_allocated() && Dart::IsRunningPrecompiledCode()) {
     return Api::NewError("Precompilation dropped '%s'", cls.ToCString());
   }
 #endif
   const Error& error = Error::Handle(Z, cls.EnsureIsFinalized(T));
   if (!error.IsNull()) {
     // An error occurred, return error object.
-    return Api::NewHandle(I, error.raw());
+    return Api::NewHandle(T, error.raw());
   }
   if (num_native_fields != cls.num_native_fields()) {
     return Api::NewError(
         "%s: invalid number of native fields %" Pd " passed in, expected %d",
         CURRENT_FUNC, num_native_fields, cls.num_native_fields());
   }
   const Instance& instance = Instance::Handle(Z, AllocateObject(T, cls));
   instance.SetNativeFields(num_native_fields, native_fields);
-  return Api::NewHandle(I, instance.raw());
+  return Api::NewHandle(T, instance.raw());
 }
 
 
 static Dart_Handle SetupArguments(Thread* thread,
                                   int num_args,
                                   Dart_Handle* arguments,
                                   int extra_args,
                                   Array* args) {
   Zone* zone = thread->zone();
-  Isolate* isolate = thread->isolate();
   // Check for malformed arguments in the arguments list.
   *args = Array::New(num_args + extra_args);
   Object& arg = Object::Handle(zone);
   for (int i = 0; i < num_args; i++) {
     arg = Api::UnwrapHandle(arguments[i]);
     if (!arg.IsNull() && !arg.IsInstance()) {
       *args = Array::null();
       if (arg.IsError()) {
-        return Api::NewHandle(isolate, arg.raw());
+        return Api::NewHandle(thread, arg.raw());
       } else {
         return Api::NewError(
             "%s expects arguments[%d] to be an Instance handle.",
             "Dart_Invoke", i);
       }
     }
     args->SetAt((i + extra_args), arg);
   }
   return Api::Success();
 }
@@ skipping 57 matching lines @@
     Dart_Handle result;
     Array& args = Array::Handle(Z);
     result = SetupArguments(T,
         number_of_arguments, arguments, extra_args, &args);
     if (!::Dart_IsError(result)) {
       args.SetAt(0, instance);
       args.SetAt(1, Smi::Handle(Z, Smi::New(Function::kCtorPhaseAll)));
       const Object& retval = Object::Handle(Z,
           DartEntry::InvokeFunction(constructor, args));
       if (retval.IsError()) {
-        result = Api::NewHandle(I, retval.raw());
+        result = Api::NewHandle(T, retval.raw());
       } else {
-        result = Api::NewHandle(I, instance.raw());
+        result = Api::NewHandle(T, instance.raw());
       }
     }
     return result;
   }
   return Api::NewError(
       "%s expects argument 'name' to be a valid constructor.",
       CURRENT_FUNC);
 }
 
 
@@ skipping 35 matching lines @@
     if (function.IsNull()) {
       const String& cls_name = String::Handle(Z, cls.Name());
       return Api::NewError("%s: did not find static method '%s.%s'.",
                            CURRENT_FUNC,
                            cls_name.ToCString(),
                            function_name.ToCString());
     }
     // Setup args and check for malformed arguments in the arguments list.
     result = SetupArguments(T, number_of_arguments, arguments, 0, &args);
     if (!::Dart_IsError(result)) {
-      result = Api::NewHandle(I, DartEntry::InvokeFunction(function, args));
+      result = Api::NewHandle(T, DartEntry::InvokeFunction(function, args));
     }
     return result;
   } else if (obj.IsNull() || obj.IsInstance()) {
     // Since we have allocated an object it would mean that the type of the
     // receiver is already resolved and finalized, hence it is not necessary
     // to check here.
     Instance& instance = Instance::Handle(Z);
     instance ^= obj.raw();
     ArgumentsDescriptor args_desc(
         Array::Handle(Z, ArgumentsDescriptor::New(number_of_arguments + 1)));
     const Function& function = Function::Handle(Z,
         Resolver::ResolveDynamic(instance, function_name, args_desc));
     if (function.IsNull()) {
       // Setup args and check for malformed arguments in the arguments list.
       result = SetupArguments(T,
                               number_of_arguments,
                               arguments,
                               1,
                               &args);
       if (!::Dart_IsError(result)) {
         args.SetAt(0, instance);
         const Array& args_descriptor =
           Array::Handle(Z, ArgumentsDescriptor::New(args.Length()));
-        result = Api::NewHandle(I,
+        result = Api::NewHandle(T,
                                 DartEntry::InvokeNoSuchMethod(instance,
                                                               function_name,
                                                               args,
                                                               args_descriptor));
       }
       return result;
     }
     // Setup args and check for malformed arguments in the arguments list.
     result = SetupArguments(T, number_of_arguments, arguments, 1, &args);
     if (!::Dart_IsError(result)) {
       args.SetAt(0, instance);
-      result = Api::NewHandle(I, DartEntry::InvokeFunction(function, args));
+      result = Api::NewHandle(T, DartEntry::InvokeFunction(function, args));
     }
     return result;
   } else if (obj.IsLibrary()) {
     // Check whether class finalization is needed.
     const Library& lib = Library::Cast(obj);
 
     // Check that the library is loaded.
     if (!lib.Loaded()) {
       return Api::NewError(
           "%s expects library argument 'target' to be loaded.",
@@ skipping 14 matching lines @@
                                          0,
                                          &error_message)) {
       return Api::NewError("%s: wrong argument count for function '%s': %s.",
                            CURRENT_FUNC,
                            function_name.ToCString(),
                            error_message.ToCString());
     }
     // Setup args and check for malformed arguments in the arguments list.
     result = SetupArguments(T, number_of_arguments, arguments, 0, &args);
     if (!::Dart_IsError(result)) {
-      result = Api::NewHandle(I, DartEntry::InvokeFunction(function, args));
+      result = Api::NewHandle(T, DartEntry::InvokeFunction(function, args));
     }
     return result;
   } else {
     return Api::NewError(
         "%s expects argument 'target' to be an object, type, or library.",
         CURRENT_FUNC);
   }
 }
 
 
@@ skipping 17 matching lines @@
   Object& obj = Object::Handle(Z);
   args.SetAt(0, closure_obj);
   for (int i = 0; i < number_of_arguments; i++) {
     obj = Api::UnwrapHandle(arguments[i]);
     if (!obj.IsNull() && !obj.IsInstance()) {
       RETURN_TYPE_ERROR(Z, arguments[i], Instance);
     }
     args.SetAt(i + 1, obj);
   }
   // Now try to invoke the closure.
-  return Api::NewHandle(I, DartEntry::InvokeClosure(args));
+  return Api::NewHandle(T, DartEntry::InvokeClosure(args));
 }
 
 
 DART_EXPORT Dart_Handle Dart_GetField(Dart_Handle container, Dart_Handle name) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
 
   const String& field_name = Api::UnwrapStringHandle(Z, name);
   if (field_name.IsNull()) {
     RETURN_TYPE_ERROR(Z, name, String);
@@ skipping 17 matching lines @@
 
     field = cls.LookupStaticField(field_name);
     if (field.IsNull() || field.IsUninitialized()) {
       const String& getter_name =
           String::Handle(Z, Field::GetterName(field_name));
       getter = cls.LookupStaticFunctionAllowPrivate(getter_name);
     }
 
     if (!getter.IsNull()) {
       // Invoke the getter and return the result.
-      return Api::NewHandle(I,
+      return Api::NewHandle(T,
           DartEntry::InvokeFunction(getter, Object::empty_array()));
     } else if (!field.IsNull()) {
-      return Api::NewHandle(I, field.StaticValue());
+      return Api::NewHandle(T, field.StaticValue());
     } else {
       return Api::NewError("%s: did not find static field '%s'.",
                            CURRENT_FUNC, field_name.ToCString());
     }
 
   } else if (obj.IsInstance()) {
     // Every instance field has a getter Function.  Try to find the
     // getter in any superclass and use that function to access the
     // field.
     const Instance& instance = Instance::Cast(obj);
     Class& cls = Class::Handle(Z, instance.clazz());
     String& getter_name = String::Handle(Z, Field::GetterName(field_name));
     while (!cls.IsNull()) {
       getter = cls.LookupDynamicFunctionAllowPrivate(getter_name);
       if (!getter.IsNull()) {
         break;
       }
       cls = cls.SuperClass();
     }
 
     // Invoke the getter and return the result.
     const int kNumArgs = 1;
     const Array& args = Array::Handle(Z, Array::New(kNumArgs));
     args.SetAt(0, instance);
     if (getter.IsNull()) {
       const Array& args_descriptor =
           Array::Handle(Z, ArgumentsDescriptor::New(args.Length()));
-      return Api::NewHandle(I,
+      return Api::NewHandle(T,
                             DartEntry::InvokeNoSuchMethod(instance,
                                                           getter_name,
                                                           args,
                                                           args_descriptor));
     }
-    return Api::NewHandle(I, DartEntry::InvokeFunction(getter, args));
+    return Api::NewHandle(T, DartEntry::InvokeFunction(getter, args));
 
   } else if (obj.IsLibrary()) {
     // To access a top-level we may need to use the Field or the
     // getter Function.  The getter function may either be in the
     // library or in the field's owner class, depending.
     const Library& lib = Library::Cast(obj);
     // Check that the library is loaded.
     if (!lib.Loaded()) {
       return Api::NewError(
           "%s expects library argument 'container' to be loaded.",
           CURRENT_FUNC);
     }
     field = lib.LookupFieldAllowPrivate(field_name);
     if (field.IsNull()) {
       // No field found and no ambiguity error.  Check for a getter in the lib.
       const String& getter_name =
           String::Handle(Z, Field::GetterName(field_name));
       getter = lib.LookupFunctionAllowPrivate(getter_name);
     } else if (!field.IsNull() && field.IsUninitialized()) {
       // A field was found.  Check for a getter in the field's owner classs.
       const Class& cls = Class::Handle(Z, field.owner());
       const String& getter_name = String::Handle(Z,
           Field::GetterName(field_name));
       getter = cls.LookupStaticFunctionAllowPrivate(getter_name);
     }
 
     if (!getter.IsNull()) {
       // Invoke the getter and return the result.
-      return Api::NewHandle(I,
+      return Api::NewHandle(T,
           DartEntry::InvokeFunction(getter, Object::empty_array()));
     }
     if (!field.IsNull()) {
-      return Api::NewHandle(I, field.StaticValue());
+      return Api::NewHandle(T, field.StaticValue());
     }
     return Api::NewError("%s: did not find top-level variable '%s'.",
                          CURRENT_FUNC, field_name.ToCString());
 
   } else if (obj.IsError()) {
       return container;
   } else {
     return Api::NewError(
         "%s expects argument 'container' to be an object, type, or library.",
         CURRENT_FUNC);
@@ skipping 44 matching lines @@
     }
 
     if (!setter.IsNull()) {
       // Invoke the setter and return the result.
       const int kNumArgs = 1;
       const Array& args = Array::Handle(Z, Array::New(kNumArgs));
       args.SetAt(0, value_instance);
       const Object& result = Object::Handle(Z,
           DartEntry::InvokeFunction(setter, args));
       if (result.IsError()) {
-        return Api::NewHandle(I, result.raw());
+        return Api::NewHandle(T, result.raw());
       } else {
         return Api::Success();
       }
     } else if (!field.IsNull()) {
       if (field.is_final()) {
         return Api::NewError("%s: cannot set final field '%s'.",
                              CURRENT_FUNC, field_name.ToCString());
       } else {
         field.SetStaticValue(value_instance);
         return Api::Success();
@@ skipping 24 matching lines @@
     }
 
     // Invoke the setter and return the result.
     const int kNumArgs = 2;
     const Array& args = Array::Handle(Z, Array::New(kNumArgs));
     args.SetAt(0, instance);
     args.SetAt(1, value_instance);
     if (setter.IsNull()) {
       const Array& args_descriptor =
           Array::Handle(Z, ArgumentsDescriptor::New(args.Length()));
-      return Api::NewHandle(I, DartEntry::InvokeNoSuchMethod(instance,
+      return Api::NewHandle(T, DartEntry::InvokeNoSuchMethod(instance,
                                                              setter_name,
                                                              args,
                                                              args_descriptor));
     }
-    return Api::NewHandle(I, DartEntry::InvokeFunction(setter, args));
+    return Api::NewHandle(T, DartEntry::InvokeFunction(setter, args));
 
   } else if (obj.IsLibrary()) {
     // To access a top-level we may need to use the Field or the
     // setter Function.  The setter function may either be in the
     // library or in the field's owner class, depending.
     const Library& lib = Library::Cast(obj);
     // Check that the library is loaded.
     if (!lib.Loaded()) {
       return Api::NewError(
           "%s expects library argument 'container' to be loaded.",
           CURRENT_FUNC);
     }
     field = lib.LookupFieldAllowPrivate(field_name);
     if (field.IsNull()) {
       const String& setter_name =
           String::Handle(Z, Field::SetterName(field_name));
       setter ^= lib.LookupFunctionAllowPrivate(setter_name);
     }
 
     if (!setter.IsNull()) {
       // Invoke the setter and return the result.
       const int kNumArgs = 1;
       const Array& args = Array::Handle(Z, Array::New(kNumArgs));
       args.SetAt(0, value_instance);
       const Object& result =
           Object::Handle(Z, DartEntry::InvokeFunction(setter, args));
       if (result.IsError()) {
-        return Api::NewHandle(I, result.raw());
+        return Api::NewHandle(T, result.raw());
       }
       return Api::Success();
     }
     if (!field.IsNull()) {
       if (field.is_final()) {
         return Api::NewError("%s: cannot set final top-level variable '%s'.",
                              CURRENT_FUNC, field_name.ToCString());
       }
       field.SetStaticValue(value_instance);
       return Api::Success();
@@ skipping 25 matching lines @@
     }
   }
   if (thread->top_exit_frame_info() == 0) {
     // There are no dart frames on the stack so it would be illegal to
     // throw an exception here.
     return Api::NewError("No Dart frames on stack, cannot throw exception");
   }
 
   // Unwind all the API scopes till the exit frame before throwing an
   // exception.
-  ApiState* state = isolate->api_state();
-  ASSERT(state != NULL);
   const Instance* saved_exception;
   {
     NoSafepointScope no_safepoint;
     RawInstance* raw_exception =
         Api::UnwrapInstanceHandle(zone, exception).raw();
-    state->UnwindScopes(thread->top_exit_frame_info());
+    thread->UnwindScopes(thread->top_exit_frame_info());
     saved_exception = &Instance::Handle(raw_exception);
   }
   Exceptions::Throw(thread, *saved_exception);
   return Api::NewError("Exception was not thrown, internal error");
 }
 
 
 DART_EXPORT Dart_Handle Dart_ReThrowException(Dart_Handle exception,
                                               Dart_Handle stacktrace) {
   Thread* thread = Thread::Current();
@@ skipping 12 matching lines @@
     }
   }
   if (thread->top_exit_frame_info() == 0) {
     // There are no dart frames on the stack so it would be illegal to
     // throw an exception here.
     return Api::NewError("No Dart frames on stack, cannot throw exception");
   }
 
   // Unwind all the API scopes till the exit frame before throwing an
   // exception.
-  ApiState* state = isolate->api_state();
-  ASSERT(state != NULL);
   const Instance* saved_exception;
   const Stacktrace* saved_stacktrace;
   {
     NoSafepointScope no_safepoint;
     RawInstance* raw_exception =
         Api::UnwrapInstanceHandle(zone, exception).raw();
     RawStacktrace* raw_stacktrace =
         Api::UnwrapStacktraceHandle(zone, stacktrace).raw();
-    state->UnwindScopes(thread->top_exit_frame_info());
+    thread->UnwindScopes(thread->top_exit_frame_info());
     saved_exception = &Instance::Handle(raw_exception);
     saved_stacktrace = &Stacktrace::Handle(raw_stacktrace);
   }
   Exceptions::ReThrow(thread, *saved_exception, *saved_stacktrace);
   return Api::NewError("Exception was not re thrown, internal error");
 }
 
 
 // --- Native fields and functions ---
 
@@ skipping 15 matching lines @@
   }
   CHECK_CALLBACK_STATE(T);
 
   String& cls_symbol = String::Handle(Z, Symbols::New(cls_name));
   const Class& cls = Class::Handle(Z,
       Class::NewNativeWrapper(lib, cls_symbol, field_count));
   if (cls.IsNull()) {
     return Api::NewError(
         "Unable to create native wrapper class : already exists");
   }
-  return Api::NewHandle(I, cls.RareType());
+  return Api::NewHandle(T, cls.RareType());
 }
 
 
 DART_EXPORT Dart_Handle Dart_GetNativeInstanceFieldCount(Dart_Handle obj,
                                                          int* count) {
   Thread* thread = Thread::Current();
   CHECK_ISOLATE(thread->isolate());
   ReusableObjectHandleScope reused_obj_handle(thread);
   const Instance& instance = Api::UnwrapInstanceHandle(reused_obj_handle, obj);
   if (instance.IsNull()) {
@@ skipping 159 matching lines @@
             native_value->as_native_fields.num_fields,
             native_value->as_native_fields.values,
             CURRENT_FUNC);
         if (result != Api::Success()) {
           return result;
         }
         break;
       }
 
       case Dart_NativeArgument_kInstance: {
-        Isolate* isolate = arguments->thread()->isolate();
-        ASSERT(isolate == Isolate::Current());
-        ASSERT(isolate->api_state() &&
-               isolate->api_state()->top_scope() != NULL);
-        native_value->as_instance =
-            Api::NewHandle(isolate, arguments->NativeArgAt(arg_index));
+        ASSERT(arguments->thread() == Thread::Current());
+        ASSERT(arguments->thread()->api_top_scope() != NULL);
+        native_value->as_instance = Api::NewHandle(
+            arguments->thread(), arguments->NativeArgAt(arg_index));
         break;
       }
 
       default:
         return Api::NewError("%s: invalid argument type %d.",
                              CURRENT_FUNC, arg_type);
     }
   }
   return Api::Success();
 }
 
 
 DART_EXPORT Dart_Handle Dart_GetNativeArgument(Dart_NativeArguments args,
                                                int index) {
   TRACE_API_CALL(CURRENT_FUNC);
   NativeArguments* arguments = reinterpret_cast<NativeArguments*>(args);
   if ((index < 0) || (index >= arguments->NativeArgCount())) {
     return Api::NewError(
         "%s: argument 'index' out of range. Expected 0..%d but saw %d.",
         CURRENT_FUNC, arguments->NativeArgCount() - 1, index);
   }
-  return Api::NewHandle(arguments->thread()->isolate(),
+  return Api::NewHandle(arguments->thread(),
                         arguments->NativeArgAt(index));
 }
 
 
 DART_EXPORT int Dart_GetNativeArgumentCount(Dart_NativeArguments args) {
   TRACE_API_CALL(CURRENT_FUNC);
   NativeArguments* arguments = reinterpret_cast<NativeArguments*>(args);
   return arguments->NativeArgCount();
 }
 
@@ skipping 129 matching lines @@
 }
 
 
 // --- Environment ---
 RawString* Api::CallEnvironmentCallback(Thread* thread, const String& name) {
   Isolate* isolate = thread->isolate();
   Scope api_scope(thread);
   Dart_EnvironmentCallback callback = isolate->environment_callback();
   String& result = String::Handle(thread->zone());
   if (callback != NULL) {
-    Dart_Handle response = callback(Api::NewHandle(isolate, name.raw()));
+    Dart_Handle response = callback(Api::NewHandle(thread, name.raw()));
     if (::Dart_IsString(response)) {
       result ^= Api::UnwrapHandle(response);
     } else if (::Dart_IsError(response)) {
       const Object& error = Object::Handle(
           thread->zone(), Api::UnwrapHandle(response));
       Exceptions::ThrowArgumentError(
           String::Handle(String::New(Error::Cast(error).ToErrorCString())));
     } else if (!::Dart_IsNull(response)) {
       // At this point everything except null are invalid environment values.
       Exceptions::ThrowArgumentError(
@@ skipping 73 matching lines @@
                           Dart_Handle* result) {
   bool update_lib_status = (script.kind() == RawScript::kScriptTag ||
                             script.kind() == RawScript::kLibraryTag);
   if (update_lib_status) {
     lib.SetLoadInProgress();
   }
   ASSERT(thread != NULL);
   const Error& error =
       Error::Handle(thread->zone(), Compiler::Compile(lib, script));
   if (error.IsNull()) {
-    *result = Api::NewHandle(thread->isolate(), lib.raw());
+    *result = Api::NewHandle(thread, lib.raw());
   } else {
-    *result = Api::NewHandle(thread->isolate(), error.raw());
+    *result = Api::NewHandle(thread, error.raw());
     // Compilation errors are not Dart instances, so just mark the library
     // as having failed to load without providing an error instance.
     lib.SetLoadError(Object::null_instance());
   }
 }
 
 
 DART_EXPORT Dart_Handle Dart_LoadScript(Dart_Handle url,
                                         Dart_Handle source,
                                         intptr_t line_offset,
                                         intptr_t column_offset) {
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   const String& url_str = Api::UnwrapStringHandle(Z, url);
   if (url_str.IsNull()) {
     RETURN_TYPE_ERROR(Z, url, String);
   }
   const String& source_str = Api::UnwrapStringHandle(Z, source);
   if (source_str.IsNull()) {
     RETURN_TYPE_ERROR(Z, source, String);
   }
   Library& library = Library::Handle(Z, I->object_store()->root_library());
   if (!library.IsNull()) {
@@ skipping 24 matching lines @@
   script.SetLocationOffset(line_offset, column_offset);
   Dart_Handle result;
   CompileSource(T, library, script, &result);
   return result;
 }
 
 
 DART_EXPORT Dart_Handle Dart_LoadScriptFromSnapshot(const uint8_t* buffer,
                                                     intptr_t buffer_len) {
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   StackZone zone(T);
   if (buffer == NULL) {
     RETURN_NULL_ERROR(buffer);
   }
   NoHeapGrowthControlScope no_growth_control;
 
   const Snapshot* snapshot = Snapshot::SetupFromBuffer(buffer);
   if (!snapshot->IsScriptSnapshot()) {
     return Api::NewError("%s expects parameter 'buffer' to be a script type"
                          " snapshot.", CURRENT_FUNC);
   }
   if (snapshot->length() != buffer_len) {
     return Api::NewError("%s: 'buffer_len' of %" Pd " is not equal to %" Pd
                          " which is the expected length in the snapshot.",
                          CURRENT_FUNC, buffer_len, snapshot->length());
   }
   Library& library = Library::Handle(Z, I->object_store()->root_library());
   if (!library.IsNull()) {
     const String& library_url = String::Handle(Z, library.url());
     return Api::NewError("%s: A script has already been loaded from '%s'.",
                          CURRENT_FUNC, library_url.ToCString());
   }
   CHECK_CALLBACK_STATE(T);
   CHECK_COMPILATION_ALLOWED(I);
 
   ASSERT(snapshot->kind() == Snapshot::kScript);
   ScriptSnapshotReader reader(snapshot->content(), snapshot->length(), T);
   const Object& tmp = Object::Handle(Z, reader.ReadScriptSnapshot());
   if (tmp.IsError()) {
-    return Api::NewHandle(I, tmp.raw());
+    return Api::NewHandle(T, tmp.raw());
   }
   library ^= tmp.raw();
   library.set_debuggable(true);
   I->object_store()->set_root_library(library);
-  return Api::NewHandle(I, library.raw());
+  return Api::NewHandle(T, library.raw());
 }
 
 
 DART_EXPORT Dart_Handle Dart_RootLibrary() {
-  Isolate* isolate = Isolate::Current();
+  Thread* thread = Thread::Current();
+  Isolate* isolate = thread->isolate();
   CHECK_ISOLATE(isolate);
-  return Api::NewHandle(isolate, isolate->object_store()->root_library());
+  return Api::NewHandle(thread, isolate->object_store()->root_library());
 }
 
 
 DART_EXPORT Dart_Handle Dart_SetRootLibrary(Dart_Handle library) {
   DARTSCOPE(Thread::Current());
   const Library& lib = Api::UnwrapLibraryHandle(Z, library);
   if (lib.IsNull()) {
     RETURN_TYPE_ERROR(Z, library, Library);
   }
   Isolate* isolate = Isolate::Current();
@@ skipping 13 matching lines @@
   if (cls_name.IsNull()) {
     RETURN_TYPE_ERROR(Z, class_name, String);
   }
   const Class& cls = Class::Handle(Z, lib.LookupClassAllowPrivate(cls_name));
   if (cls.IsNull()) {
     // TODO(turnidge): Return null or error in this case?
     const String& lib_name = String::Handle(Z, lib.name());
     return Api::NewError("Class '%s' not found in library '%s'.",
                          cls_name.ToCString(), lib_name.ToCString());
   }
-  return Api::NewHandle(I, cls.RareType());
+  return Api::NewHandle(T, cls.RareType());
 }
 
 
 DART_EXPORT Dart_Handle Dart_GetType(Dart_Handle library,
                                      Dart_Handle class_name,
                                      intptr_t number_of_type_arguments,
                                      Dart_Handle* type_arguments) {
   DARTSCOPE(Thread::Current());
 
   // Validate the input arguments.
@@ skipping 14 matching lines @@
   if (cls.IsNull()) {
     const String& lib_name = String::Handle(Z, lib.name());
     return Api::NewError("Type '%s' not found in library '%s'.",
                          name_str.ToCString(), lib_name.ToCString());
   }
   if (cls.NumTypeArguments() == 0) {
     if (number_of_type_arguments != 0) {
       return Api::NewError("Invalid number of type arguments specified, "
                            "got %" Pd " expected 0", number_of_type_arguments);
     }
-    return Api::NewHandle(I, Type::NewNonParameterizedType(cls));
+    return Api::NewHandle(T, Type::NewNonParameterizedType(cls));
   }
   intptr_t num_expected_type_arguments = cls.NumTypeParameters();
   TypeArguments& type_args_obj = TypeArguments::Handle();
   if (number_of_type_arguments > 0) {
     if (type_arguments == NULL) {
       RETURN_NULL_ERROR(type_arguments);
     }
     if (num_expected_type_arguments != number_of_type_arguments) {
       return Api::NewError("Invalid number of type arguments specified, "
                            "got %" Pd " expected %" Pd,
@@ skipping 17 matching lines @@
       type_arg ^= array.At(i);
       type_args_obj.SetTypeAt(i, type_arg);
     }
   }
 
   // Construct the type object, canonicalize it and return.
   Type& instantiated_type = Type::Handle(
       Type::New(cls, type_args_obj, Scanner::kNoSourcePos));
   instantiated_type ^= ClassFinalizer::FinalizeType(
       cls, instantiated_type, ClassFinalizer::kCanonicalize);
-  return Api::NewHandle(I, instantiated_type.raw());
+  return Api::NewHandle(T, instantiated_type.raw());
 }
 
 
 DART_EXPORT Dart_Handle Dart_LibraryUrl(Dart_Handle library) {
   DARTSCOPE(Thread::Current());
   const Library& lib = Api::UnwrapLibraryHandle(Z, library);
   if (lib.IsNull()) {
     RETURN_TYPE_ERROR(Z, library, Library);
   }
   const String& url = String::Handle(Z, lib.url());
   ASSERT(!url.IsNull());
-  return Api::NewHandle(I, url.raw());
+  return Api::NewHandle(T, url.raw());
 }
 
 
 DART_EXPORT Dart_Handle Dart_LookupLibrary(Dart_Handle url) {
   DARTSCOPE(Thread::Current());
   const String& url_str = Api::UnwrapStringHandle(Z, url);
   if (url_str.IsNull()) {
     RETURN_TYPE_ERROR(Z, url, String);
   }
   const Library& library = Library::Handle(Z, Library::LookupLibrary(url_str));
   if (library.IsNull()) {
     return Api::NewError("%s: library '%s' not found.",
                          CURRENT_FUNC, url_str.ToCString());
   } else {
-    return Api::NewHandle(I, library.raw());
+    return Api::NewHandle(T, library.raw());
   }
 }
 
 
 DART_EXPORT Dart_Handle Dart_LibraryHandleError(Dart_Handle library_in,
                                                 Dart_Handle error_in) {
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
 
   const Library& lib = Api::UnwrapLibraryHandle(Z, library_in);
   if (lib.IsNull()) {
     RETURN_TYPE_ERROR(Z, library_in, Library);
   }
   const Instance& err = Api::UnwrapInstanceHandle(Z, error_in);
   if (err.IsNull()) {
     RETURN_TYPE_ERROR(Z, error_in, Instance);
   }
   CHECK_CALLBACK_STATE(T);
 
   const GrowableObjectArray& pending_deferred_loads =
       GrowableObjectArray::Handle(Z,
           I->object_store()->pending_deferred_loads());
   for (intptr_t i = 0; i < pending_deferred_loads.Length(); i++) {
     if (pending_deferred_loads.At(i) == lib.raw()) {
       lib.SetLoadError(err);
       return Api::Null();
     }
   }
   return error_in;
 }
 
 
 DART_EXPORT Dart_Handle Dart_LoadLibrary(Dart_Handle url,
                                          Dart_Handle source,
                                          intptr_t line_offset,
                                          intptr_t column_offset) {
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   const String& url_str = Api::UnwrapStringHandle(Z, url);
   if (url_str.IsNull()) {
     RETURN_TYPE_ERROR(Z, url, String);
   }
   const String& source_str = Api::UnwrapStringHandle(Z, source);
   if (source_str.IsNull()) {
     RETURN_TYPE_ERROR(Z, source, String);
   }
   if (line_offset < 0) {
     return Api::NewError("%s: argument 'line_offset' must be positive number",
@@ skipping 26 matching lines @@
   Dart_Handle result;
   CompileSource(T, library, script, &result);
   // Propagate the error out right now.
   if (::Dart_IsError(result)) {
     return result;
   }
 
   // If this is the dart:_builtin library, register it with the VM.
   if (url_str.Equals("dart:_builtin")) {
     I->object_store()->set_builtin_library(library);
-    Dart_Handle state = Api::CheckAndFinalizePendingClasses(I);
+    Dart_Handle state = Api::CheckAndFinalizePendingClasses(T);
     if (::Dart_IsError(state)) {
       return state;
     }
   }
   return result;
 }
 
 
 DART_EXPORT Dart_Handle Dart_LibraryImportLibrary(Dart_Handle library,
                                                   Dart_Handle import,
                                                   Dart_Handle prefix) {
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   const Library& library_vm = Api::UnwrapLibraryHandle(Z, library);
   if (library_vm.IsNull()) {
     RETURN_TYPE_ERROR(Z, library, Library);
   }
   const Library& import_vm = Api::UnwrapLibraryHandle(Z, import);
   if (import_vm.IsNull()) {
     RETURN_TYPE_ERROR(Z, import, Library);
   }
   const Object& prefix_object = Object::Handle(Z, Api::UnwrapHandle(prefix));
   const String& prefix_vm = prefix_object.IsNull()
@@ skipping 24 matching lines @@
   return Api::Success();
 }
 
 
 DART_EXPORT Dart_Handle Dart_LoadSource(Dart_Handle library,
                                         Dart_Handle url,
                                         Dart_Handle source,
                                         intptr_t line_offset,
                                         intptr_t column_offset) {
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   const Library& lib = Api::UnwrapLibraryHandle(Z, library);
   if (lib.IsNull()) {
     RETURN_TYPE_ERROR(Z, library, Library);
   }
   const String& url_str = Api::UnwrapStringHandle(Z, url);
   if (url_str.IsNull()) {
     RETURN_TYPE_ERROR(Z, url, String);
   }
   const String& source_str = Api::UnwrapStringHandle(Z, source);
   if (source_str.IsNull()) {
@@ skipping 18 matching lines @@
   Dart_Handle result;
   CompileSource(T, lib, script, &result);
   return result;
 }
 
 
 DART_EXPORT Dart_Handle Dart_LibraryLoadPatch(Dart_Handle library,
                                               Dart_Handle url,
                                               Dart_Handle patch_source) {
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   const Library& lib = Api::UnwrapLibraryHandle(Z, library);
   if (lib.IsNull()) {
     RETURN_TYPE_ERROR(Z, library, Library);
   }
   const String& url_str = Api::UnwrapStringHandle(Z, url);
   if (url_str.IsNull()) {
     RETURN_TYPE_ERROR(Z, url, String);
   }
   const String& source_str = Api::UnwrapStringHandle(Z, patch_source);
   if (source_str.IsNull()) {
     RETURN_TYPE_ERROR(Z, patch_source, String);
   }
   CHECK_CALLBACK_STATE(T);
   CHECK_COMPILATION_ALLOWED(I);
 
   NoHeapGrowthControlScope no_growth_control;
 
   const Script& script = Script::Handle(Z,
       Script::New(url_str, source_str, RawScript::kPatchTag));
   Dart_Handle result;
   CompileSource(T, lib, script, &result);
   return result;
 }
 
 
 // Finalizes classes and invokes Dart core library function that completes
 // futures of loadLibrary calls (deferred library loading).
 DART_EXPORT Dart_Handle Dart_FinalizeLoading(bool complete_futures) {
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   CHECK_CALLBACK_STATE(T);
 
   I->DoneLoading();
 
   // TODO(hausner): move the remaining code below (finalization and
   // invoing of _completeDeferredLoads) into Isolate::DoneLoading().
 
   // Finalize all classes if needed.
-  Dart_Handle state = Api::CheckAndFinalizePendingClasses(I);
+  Dart_Handle state = Api::CheckAndFinalizePendingClasses(T);
   if (::Dart_IsError(state)) {
     return state;
   }
 
   // Now that the newly loaded classes are finalized, notify the debugger
   // that new code has been loaded. If there are latent breakpoints in
   // the new code, the debugger convert them to unresolved source breakpoints.
   // The code that completes the futures (invoked below) may call into the
   // newly loaded code and trigger one of these breakpoints.
   I->debugger()->NotifyDoneLoading();
@@ skipping 11 matching lines @@
         String::Handle(Z, String::New("_completeDeferredLoads"));
     const Function& function = Function::Handle(Z,
         corelib.LookupFunctionAllowPrivate(function_name));
     ASSERT(!function.IsNull());
     const Array& args = Array::empty_array();
 
     const Object& res =
         Object::Handle(Z, DartEntry::InvokeFunction(function, args));
     I->object_store()->clear_pending_deferred_loads();
     if (res.IsError() || res.IsUnhandledException()) {
-      return Api::NewHandle(I, res.raw());
+      return Api::NewHandle(T, res.raw());
     }
   }
   return Api::Success();
 }
 
 
 DART_EXPORT Dart_Handle Dart_SetNativeResolver(
     Dart_Handle library,
     Dart_NativeEntryResolver resolver,
     Dart_NativeEntrySymbol symbol) {
@@ skipping 116 matching lines @@
   Service::SetEmbedderStreamCallbacks(listen_callback, cancel_callback);
   return Api::Success();
 }
 
 
 DART_EXPORT Dart_Handle Dart_ServiceSendDataEvent(const char* stream_id,
                                                   const char* event_kind,
                                                   const uint8_t* bytes,
                                                   intptr_t bytes_length) {
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   if (stream_id == NULL) {
     RETURN_NULL_ERROR(stream_id);
   }
   if (event_kind == NULL) {
     RETURN_NULL_ERROR(event_kind);
   }
   if (bytes == NULL) {
     RETURN_NULL_ERROR(bytes);
   }
   if (bytes_length < 0) {
@@ skipping 307 matching lines @@
 }
 
 
 DART_EXPORT Dart_Handle Dart_Precompile(
     Dart_QualifiedFunctionName entry_points[],
     bool reset_fields) {
   DARTSCOPE(Thread::Current());
   if (!FLAG_precompilation) {
     return Dart_NewApiError("Flag --precompilation was not specified.");
   }
-  Dart_Handle result = Api::CheckAndFinalizePendingClasses(I);
+  Dart_Handle result = Api::CheckAndFinalizePendingClasses(T);
   if (::Dart_IsError(result)) {
     return result;
   }
   CHECK_CALLBACK_STATE(T);
   const Error& error = Error::Handle(Precompiler::CompileAll(entry_points,
                                                              reset_fields));
   if (!error.IsNull()) {
-    return Api::NewHandle(I, error.raw());
+    return Api::NewHandle(T, error.raw());
   }
   return Api::Success();
 }
 
 
 DART_EXPORT Dart_Handle Dart_CreatePrecompiledSnapshot(
     uint8_t** vm_isolate_snapshot_buffer,
     intptr_t* vm_isolate_snapshot_size,
     uint8_t** isolate_snapshot_buffer,
     intptr_t* isolate_snapshot_size,
     uint8_t** instructions_snapshot_buffer,
     intptr_t* instructions_snapshot_size) {
   ASSERT(FLAG_load_deferred_eagerly);
   DARTSCOPE(Thread::Current());
+  Isolate* I = T->isolate();
   if (I->compilation_allowed()) {
     return Dart_NewApiError("Isolate is not precompiled. "
                             "Did you forget to call Dart_Precompile?");
   }
   if (vm_isolate_snapshot_buffer == NULL) {
     RETURN_NULL_ERROR(vm_isolate_snapshot_buffer);
   }
   if (vm_isolate_snapshot_size == NULL) {
     RETURN_NULL_ERROR(vm_isolate_snapshot_size);
   }
   if (isolate_snapshot_buffer == NULL) {
     RETURN_NULL_ERROR(isolate_snapshot_buffer);
   }
   if (isolate_snapshot_size == NULL) {
     RETURN_NULL_ERROR(isolate_snapshot_size);
   }
   if (instructions_snapshot_buffer == NULL) {
     RETURN_NULL_ERROR(instructions_snapshot_buffer);
   }
   if (instructions_snapshot_size == NULL) {
     RETURN_NULL_ERROR(instructions_snapshot_size);
   }
   // Finalize all classes if needed.
-  Dart_Handle state = Api::CheckAndFinalizePendingClasses(I);
+  Dart_Handle state = Api::CheckAndFinalizePendingClasses(T);
   if (::Dart_IsError(state)) {
     return state;
   }
   I->heap()->CollectAllGarbage();
   PrecompiledSnapshotWriter writer(vm_isolate_snapshot_buffer,
                                    isolate_snapshot_buffer,
                                    instructions_snapshot_buffer,
                                    ApiReallocate);
   writer.WriteFullSnapshot();
   *vm_isolate_snapshot_size = writer.VmIsolateSnapshotSize();
   *isolate_snapshot_size = writer.IsolateSnapshotSize();
   *instructions_snapshot_size = writer.InstructionsSnapshotSize();
 
   return Api::Success();
 }
 
 }  // namespace dart