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

test/cctest/test-heap.cc

Index: test/cctest/test-heap.cc
diff --git a/test/cctest/test-heap.cc b/test/cctest/test-heap.cc
index a87c364d5f78688ca08ea4fede06aa97674c307d..e80f4f1d06dd86cc00b194f4cd66161ce6be09bb 100644
--- a/test/cctest/test-heap.cc
+++ b/test/cctest/test-heap.cc
@@ -2210,11 +2210,8 @@ TEST(PrototypeTransitionClearing) {
   // 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.