New GC APIs, try 2.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index dddcd7dcf502bb3f3216763b9477dcf724a0299f..5c2a0b0d1e3c630631736c9bfdc3bcad581f52ac 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -5925,6 +5925,23 @@ void V8::AddObjectGroup(Isolate* exported_isolate,
 }
 
 
+void V8::SetObjectGroupId(Isolate* exported_isolate,
+                          const Persistent<Value>& object,
+                          UniqueId id) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(exported_isolate);
+  isolate->global_handles()->SetObjectGroupId(
+      reinterpret_cast<i::Object**>(*object), id);
+}
+
+
+void V8::SetRetainedObjectInfo(Isolate* exported_isolate,
+                               UniqueId id,
+                               RetainedObjectInfo* info) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(exported_isolate);
+  isolate->global_handles()->SetRetainedObjectInfo(id, info);
+}
+
+
 void V8::AddImplicitReferences(Persistent<Object> parent,
                                Persistent<Value>* children,
                                size_t length) {
@@ -5937,6 +5954,15 @@ void V8::AddImplicitReferences(Persistent<Object> parent,
 }
 
 
+void V8::AddImplicitReference(Isolate* exported_isolate,
+                              UniqueId id,
+                              const Persistent<Value>& object) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(exported_isolate);
+  isolate->global_handles()
+      ->AddImplicitReference(id, reinterpret_cast<i::Object**>(*object));
+}
+
+
 intptr_t Isolate::AdjustAmountOfExternalAllocatedMemory(
     intptr_t change_in_bytes) {
   i::Heap* heap = reinterpret_cast<i::Isolate*>(this)->heap();