[heap] Hide GCTracer inside the heap component.

src/heap/mark-compact.cc

 // 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.
 
 #include "src/heap/mark-compact.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
 #include "src/cpu-profiler.h"
 #include "src/deoptimizer.h"
 #include "src/execution.h"
 #include "src/frames-inl.h"
 #include "src/gdb-jit.h"
 #include "src/global-handles.h"
+#include "src/heap/gc-tracer.h"
 #include "src/heap/incremental-marking.h"
 #include "src/heap/mark-compact-inl.h"
 #include "src/heap/objects-visiting.h"
 #include "src/heap/objects-visiting-inl.h"
 #include "src/heap/spaces-inl.h"
 #include "src/heap-profiler.h"
 #include "src/ic/ic.h"
 #include "src/ic/stub-cache.h"
 #include "src/v8.h"
 
@@ skipping 4686 matching lines @@
   SlotsBuffer* buffer = *buffer_address;
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 }  // namespace internal
 }  // namespace v8