Move a bunch of GC related files to heap/ subdirectory

src/transitions.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_TRANSITIONS_H_
 #define V8_TRANSITIONS_H_
 
 #include "src/checks.h"
 #include "src/elements-kind.h"
-#include "src/heap.h"
+#include "src/heap/heap.h"
 #include "src/isolate.h"
 #include "src/objects.h"
 
 namespace v8 {
 namespace internal {
 
 
 // TransitionArrays are fixed arrays used to hold map transitions for property,
 // constant, and element changes. They can either be simple transition arrays
 // that store a single property transition, or a full transition array that has
@@ skipping 164 matching lines @@
                                                 int origin_transition,
                                                 int target_transition);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(TransitionArray);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TRANSITIONS_H_