Remove prototype key from the prototype transitions since its also embedded in the target map.

test/cctest/test-heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2192 matching lines @@
   CHECK_EQ(initialTransitions + 10,
       baseObject->map()->NumberOfProtoTransitions());
   CcTest::heap()->CollectAllGarbage(Heap::kAbortIncrementalMarkingMask);
   const int transitions = 10 - 3;
   CHECK_EQ(initialTransitions + transitions,
       baseObject->map()->NumberOfProtoTransitions());
 
   // Verify that prototype transitions array was compacted.
   FixedArray* trans = baseObject->map()->GetPrototypeTransitions();
   for (int i = initialTransitions; i < initialTransitions + transitions; i++) {
-    int j = Map::kProtoTransitionHeaderSize +
-        i * Map::kProtoTransitionElementsPerEntry;
-    CHECK(trans->get(j + Map::kProtoTransitionMapOffset)->IsMap());
-    Object* proto = trans->get(j + Map::kProtoTransitionPrototypeOffset);
-    CHECK(proto->IsJSObject());
+    int j = Map::kProtoTransitionHeaderSize + i;
+    CHECK(trans->get(j)->IsMap());
   }
 
   // Make sure next prototype is placed on an old-space evacuation candidate.
   Handle<JSObject> prototype;
   PagedSpace* space = CcTest::heap()->old_pointer_space();
   {
     AlwaysAllocateScope always_allocate(isolate);
     SimulateFullSpace(space);
     prototype = factory->NewJSArray(32 * KB, FAST_HOLEY_ELEMENTS, TENURED);
   }
@@ skipping 2761 matching lines @@
 #ifdef DEBUG
 TEST(PathTracer) {
   CcTest::InitializeVM();
   v8::HandleScope scope(CcTest::isolate());
 
   v8::Local<v8::Value> result = CompileRun("'abc'");
   Handle<Object> o = v8::Utils::OpenHandle(*result);
   CcTest::i_isolate()->heap()->TracePathToObject(*o);
 }
 #endif  // DEBUG