Move a bunch of GC related files to heap/ subdirectory

src/contexts.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_CONTEXTS_H_
 #define V8_CONTEXTS_H_
 
-#include "src/heap.h"
+#include "src/heap/heap.h"
 #include "src/objects.h"
 
 namespace v8 {
 namespace internal {
 
 
 enum ContextLookupFlags {
   FOLLOW_CONTEXT_CHAIN = 1,
   FOLLOW_PROTOTYPE_CHAIN = 2,
 
@@ skipping 561 matching lines @@
   static bool IsBootstrappingOrGlobalObject(Isolate* isolate, Object* object);
 #endif
 
   STATIC_ASSERT(kHeaderSize == Internals::kContextHeaderSize);
   STATIC_ASSERT(EMBEDDER_DATA_INDEX == Internals::kContextEmbedderDataIndex);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_CONTEXTS_H_