Use EmbedderHeapTracer instead of object grouping when trace_embedder_heap flag is set

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 0efc8f6384816d67e7a3cd1ae6e2468bfa7dafa5..a614b09b42ffcd4828a8436a803ef7158f461fc6 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -5397,7 +5397,7 @@ class EmbedderHeapTracer {
    */
   virtual void TraceWrappableFrom(
       Isolate* isolate,
-      const std::vector<std::pair<void*, void*> >& internal_fields) = 0;
+      const std::vector<std::pair<Value*, Value*> >& internal_fields) = 0;

[jochen (gone - plz use gerrit), 2016/04/08 02:19:56]

why this change? I don't think we should expose Data* as that's internally
expected to be a Handle<Object> which this is not.

[Marcel Hlopko, 2016/04/08 08:08:09]

The motivation was to be consistent with SetInternalField, which takes
Local<Value>. I had an impression that Value represents i::Object, not
Handle<i::Object>, now I see I was wrong :) Switching back to void*.

   /**
    * V8 will call this method at the end of the gc cycle. Allocation is *not*
    * allowed in the ClearTracingMarks.
@@ -7353,7 +7353,8 @@ class Internals {
   static const int kNodeIsPartiallyDependentShift = 4;
   static const int kNodeIsActiveShift = 4;
 
-  static const int kJSObjectType = 0xb6;
+  static const int kJSObjectType = 0xb7;
+  static const int kJSApiObjectType = 0xb6;
   static const int kFirstNonstringType = 0x80;
   static const int kOddballType = 0x83;
   static const int kForeignType = 0x87;
@@ -7985,7 +7986,9 @@ Local<Value> Object::GetInternalField(int index) {
   O* obj = *reinterpret_cast<O**>(this);
   // Fast path: If the object is a plain JSObject, which is the common case, we
   // know where to find the internal fields and can return the value directly.
-  if (I::GetInstanceType(obj) == I::kJSObjectType) {
+  auto instance_type = I::GetInstanceType(obj);
+  if (instance_type == I::kJSObjectType ||
+      instance_type == I::kJSApiObjectType) {
     int offset = I::kJSObjectHeaderSize + (internal::kApiPointerSize * index);
     O* value = I::ReadField<O*>(obj, offset);
     O** result = HandleScope::CreateHandle(reinterpret_cast<HO*>(obj), value);
@@ -8003,7 +8006,9 @@ void* Object::GetAlignedPointerFromInternalField(int index) {
   O* obj = *reinterpret_cast<O**>(this);
   // Fast path: If the object is a plain JSObject, which is the common case, we
   // know where to find the internal fields and can return the value directly.
-  if (V8_LIKELY(I::GetInstanceType(obj) == I::kJSObjectType)) {
+  auto instance_type = I::GetInstanceType(obj);
+  if (V8_LIKELY(instance_type == I::kJSObjectType ||
+                instance_type == I::kJSApiObjectType)) {
     int offset = I::kJSObjectHeaderSize + (internal::kApiPointerSize * index);
     return I::ReadField<void*>(obj, offset);
   }