Move a bunch of GC related files to heap/ subdirectory

src/heap/gc-tracer.h

Index: src/heap/gc-tracer.h
diff --git a/src/gc-tracer.h b/src/heap/gc-tracer.h
similarity index 99%
rename from src/gc-tracer.h
rename to src/heap/gc-tracer.h
index d5e47af10f2b5b64c5575cc0b291e0ea89d7bbc1..e6a496eecc75cf88cea8e3bd936067e234b742d3 100644
--- a/src/gc-tracer.h
+++ b/src/heap/gc-tracer.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef V8_GC_TRACER_H_
-#define V8_GC_TRACER_H_
+#ifndef V8_HEAP_GC_TRACER_H_
+#define V8_HEAP_GC_TRACER_H_
 
 namespace v8 {
 namespace internal {
@@ -339,4 +339,4 @@ class GCTracer BASE_EMBEDDED {
 }
 }  // namespace v8::internal
 
-#endif  // V8_GC_TRACER_H_
+#endif  // V8_HEAP_GC_TRACER_H_