Revert of [runtime] Replace global object link with native context link in all contexts.

src/contexts.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/contexts.h"
 
 #include "src/ast/scopeinfo.h"
 #include "src/bootstrapper.h"
 #include "src/debug/debug.h"
 #include "src/isolate-inl.h"
@@ skipping 100 matching lines @@
   return ScopeInfo::cast(object);
 }
 
 
 String* Context::catch_name() {
   DCHECK(IsCatchContext());
   return String::cast(extension());
 }
 
 
-JSGlobalObject* Context::global_object() {
-  return JSGlobalObject::cast(native_context()->extension());
-}
-
-
 Context* Context::script_context() {
   Context* current = this;
   while (!current->IsScriptContext()) {
     current = current->previous();
   }
   return current;
 }
 
 
+Context* Context::native_context() {
+  // Fast case: the receiver context is already a native context.
+  if (IsNativeContext()) return this;
+  // The global object has a direct pointer to the native context. If the
+  // following DCHECK fails, the native context is probably being accessed
+  // indirectly during bootstrapping. This is unsupported.
+  DCHECK(global_object()->IsJSGlobalObject());
+  return global_object()->native_context();
+}
+
+
 JSObject* Context::global_proxy() {
   return native_context()->global_proxy_object();
 }
 
 
 void Context::set_global_proxy(JSObject* object) {
   native_context()->set_global_proxy_object(object);
 }
 
 
@@ skipping 399 matching lines @@
                           Handle<JSFunction> function) {
 #define COMPARE_FUNCTION(index, type, name) \
   if (*function == native_context->get(index)) return true;
   NATIVE_CONTEXT_JS_BUILTINS(COMPARE_FUNCTION);
 #undef COMPARE_FUNCTION
   return false;
 }
 
 
 #ifdef DEBUG
-
-bool Context::IsBootstrappingOrNativeContext(Isolate* isolate, Object* object) {
-  // During bootstrapping we allow all objects to pass as global
-  // objects. This is necessary to fix circular dependencies.
-  return isolate->heap()->gc_state() != Heap::NOT_IN_GC ||
-         isolate->bootstrapper()->IsActive() || object->IsNativeContext();
-}
-
-
 bool Context::IsBootstrappingOrValidParentContext(
     Object* object, Context* child) {
   // During bootstrapping we allow all objects to pass as
   // contexts. This is necessary to fix circular dependencies.
   if (child->GetIsolate()->bootstrapper()->IsActive()) return true;
   if (!object->IsContext()) return false;
   Context* context = Context::cast(object);
   return context->IsNativeContext() || context->IsScriptContext() ||
          context->IsModuleContext() || !child->IsModuleContext();
 }
 
+
+bool Context::IsBootstrappingOrGlobalObject(Isolate* isolate, Object* object) {
+  // During bootstrapping we allow all objects to pass as global
+  // objects. This is necessary to fix circular dependencies.
+  return isolate->heap()->gc_state() != Heap::NOT_IN_GC ||
+         isolate->bootstrapper()->IsActive() || object->IsJSGlobalObject();
+}
 #endif
 
 
 void Context::IncrementErrorsThrown() {
   DCHECK(IsNativeContext());
 
   int previous_value = errors_thrown()->value();
   set_errors_thrown(Smi::FromInt(previous_value + 1));
 }
 
 
 int Context::GetErrorsThrown() { return errors_thrown()->value(); }
 
 }  // namespace internal
 }  // namespace v8