Implement handlified String::Equals and Name::Equals.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index 758213719c3792678e8b2f89446ef6d34c53e5b9..8d3a7eda4f97db6491bbe3ddc46d7e3ae18d3440 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -1189,15 +1189,6 @@ class Heap {
   // NULL is returned if string is in new space or not flattened.
   Map* InternalizedStringMapForString(String* str);
 
-  // Tries to flatten a string before compare operation.
-  //
-  // Returns a failure in case it was decided that flattening was
-  // necessary and failed.  Note, if flattening is not necessary the
-  // string might stay non-flat even when not a failure is returned.
-  //
-  // Please note this function does not perform a garbage collection.
-  MUST_USE_RESULT inline MaybeObject* PrepareForCompare(String* str);
-
   // Converts the given boolean condition to JavaScript boolean value.
   inline Object* ToBoolean(bool condition);