Add script context with context-allocated "const this"

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index c675fe7e0d423211669c505a2f1a7a4169a9aa31..73dd2989a79d997cdfe20a48bd1a8e020d02a2ba 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -197,6 +197,11 @@ class Genesis BASE_EMBEDDED {
   // other objects in the snapshot.
   void HookUpGlobalObject(Handle<GlobalObject> global_object,
                           Handle<FixedArray> outdated_contexts);
+  // The native context has a ScriptContextTable that store declarative bindings
+  // made in script scopes.  Add a "this" binding to that table pointing to the
+  // global proxy.
+  void InstallGlobalThisBinding();
+  void HookUpGlobalThisBinding(Handle<FixedArray> outdated_contexts);
   // New context initialization.  Used for creating a context from scratch.
   void InitializeGlobal(Handle<GlobalObject> global_object,
                         Handle<JSFunction> empty_function);
@@ -814,6 +819,40 @@ void Genesis::CreateRoots() {
 }
 
 
+void Genesis::InstallGlobalThisBinding() {
+  Handle<ScriptContextTable> script_contexts(
+      native_context()->script_context_table());
+  Handle<ScopeInfo> scope_info = ScopeInfo::CreateGlobalThisBinding(isolate());
+  Handle<JSFunction> closure(native_context()->closure());
+  Handle<Context> context = factory()->NewScriptContext(closure, scope_info);
+
+  // Go ahead and hook it up while we're at it.
+  int slot = scope_info->ReceiverContextSlotIndex();
+  DCHECK_EQ(slot, Context::MIN_CONTEXT_SLOTS);
+  context->set(slot, native_context()->global_proxy());
+
+  native_context()->set_script_context_table(
+      *ScriptContextTable::Extend(script_contexts, context));
+}
+
+
+void Genesis::HookUpGlobalThisBinding(Handle<FixedArray> outdated_contexts) {
+  // One of these contexts should be the one that declares the global "this"
+  // binding.
+  for (int i = 0; i < outdated_contexts->length(); ++i) {
+    Context* context = Context::cast(outdated_contexts->get(i));
+    if (context->IsScriptContext()) {
+      ScopeInfo* scope_info = ScopeInfo::cast(context->extension());
+      int slot = scope_info->ReceiverContextSlotIndex();
+      if (slot >= 0) {
+        DCHECK_EQ(slot, Context::MIN_CONTEXT_SLOTS);
+        context->set(slot, native_context()->global_proxy());
+      }
+    }
+  }
+}
+
+
 Handle<GlobalObject> Genesis::CreateNewGlobals(
     v8::Handle<v8::ObjectTemplate> global_proxy_template,
     Handle<JSGlobalProxy> global_proxy) {
@@ -972,6 +1011,7 @@ void Genesis::InitializeGlobal(Handle<GlobalObject> global_object,
   Handle<ScriptContextTable> script_context_table =
       factory->NewScriptContextTable();
   native_context()->set_script_context_table(*script_context_table);
+  InstallGlobalThisBinding();
 
   Handle<String> object_name = factory->Object_string();
   JSObject::AddProperty(
@@ -3086,6 +3126,7 @@ Genesis::Genesis(Isolate* isolate,
     HookUpGlobalObject(global_object, outdated_contexts);
     native_context()->builtins()->set_global_proxy(
         native_context()->global_proxy());
+    HookUpGlobalThisBinding(outdated_contexts);
 
     if (!ConfigureGlobalObjects(global_proxy_template)) return;
   } else {