Hide heap methods where possible.

test/cctest/test-mark-compact.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 110 matching lines @@
 
   // Call mark compact GC, and it should pass.
   heap->CollectGarbage(OLD_POINTER_SPACE);
 }
 
 
 TEST(MarkCompactCollector) {
   FLAG_incremental_marking = false;
   CcTest::InitializeVM();
   Isolate* isolate = CcTest::i_isolate();
-  Heap* heap = isolate->heap();
+  TestHeap* heap = CcTest::test_heap();
   Factory* factory = isolate->factory();
 
   v8::HandleScope sc(CcTest::isolate());
   Handle<GlobalObject> global(isolate->context()->global_object());
 
   // call mark-compact when heap is empty
   heap->CollectGarbage(OLD_POINTER_SPACE, "trigger 1");
 
   // keep allocating garbage in new space until it fails
   const int ARRAY_SIZE = 100;
@@ skipping 380 matching lines @@
 
 
 TEST(RegressJoinThreadsOnIsolateDeinit) {
   intptr_t size_limit = ShortLivingIsolate() * 2;
   for (int i = 0; i < 10; i++) {
     CHECK_GT(size_limit, ShortLivingIsolate());
   }
 }
 
 #endif  // __linux__ and !USE_SIMULATOR