Auto create ApiLocalScope before calling native functions, this ensures that

runtime/vm/native_entry.cc

Index: runtime/vm/native_entry.cc
===================================================================
--- runtime/vm/native_entry.cc	(revision 25822)
+++ runtime/vm/native_entry.cc	(working copy)
@@ -7,16 +7,22 @@
 #include "include/dart_api.h"
 
 #include "vm/dart_api_impl.h"
+#include "vm/dart_api_state.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, trace_natives, false, "Trace invocation of natives");
 
-NativeFunction NativeEntry::ResolveNative(const Class& cls,
+
+static ExternalLabel native_call_label(
+    "native_function_call",
+    reinterpret_cast<uword>(&NativeEntry::NativeCallWrapper));
+
+
+NativeFunction NativeEntry::ResolveNative(const Library& library,
                                           const String& function_name,
                                           int number_of_arguments) {
   // Now resolve the native function to the corresponding native entrypoint.
-  const Library& library = Library::Handle(cls.library());
   if (library.native_entry_resolver() == 0) {
     // Native methods are not allowed in the library to which this
     // class belongs in.
@@ -31,4 +37,47 @@
   return reinterpret_cast<NativeFunction>(native_function);
 }
 
+
+const ExternalLabel& NativeEntry::NativeCallWrapperLabel() {
+  return native_call_label;
+}
+
+
+void NativeEntry::NativeCallWrapper(Dart_NativeArguments args,
+                                    Dart_NativeFunction func) {
+  CHECK_STACK_ALIGNMENT;
+  VERIFY_ON_TRANSITION;
+  NativeArguments* arguments = reinterpret_cast<NativeArguments*>(args);
+  Isolate* isolate = arguments->isolate();
+  ApiState* state = isolate->api_state();
+  ASSERT(state != NULL);
+  ApiLocalScope* current_top_scope = state->top_scope();
+  ApiLocalScope* scope = state->reusable_scope();
+  if (scope == NULL) {
+    scope = new ApiLocalScope(current_top_scope,
+                              isolate->top_exit_frame_info());
+    ASSERT(scope != NULL);
+  } else {
+    scope->Reinit(isolate,
+                  current_top_scope,
+                  isolate->top_exit_frame_info());
+    state->set_reusable_scope(NULL);
+  }
+  state->set_top_scope(scope);  // New scope is now the top scope.
+
+  func(args);
+
+  ASSERT(current_top_scope == scope->previous());
+  state->set_top_scope(current_top_scope);  // Reset top scope to previous.
+  if (state->reusable_scope() == NULL) {
+    scope->Reset(isolate);  // Reset the old scope which we just exited.
+    state->set_reusable_scope(scope);
+  } else {
+    ASSERT(state->reusable_scope() != scope);
+    delete scope;
+  }
+  DEOPTIMIZE_ALOT;
+  VERIFY_ON_TRANSITION;
+}
+
 }  // namespace dart