[heap] Hide GCTracer inside the heap component.

src/heap/incremental-marking.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/incremental-marking.h"
 
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
 #include "src/conversions.h"
+#include "src/heap/gc-tracer.h"
 #include "src/heap/mark-compact-inl.h"
 #include "src/heap/objects-visiting.h"
 #include "src/heap/objects-visiting-inl.h"
 
 namespace v8 {
 namespace internal {
 
 
 IncrementalMarking::StepActions IncrementalMarking::IdleStepActions() {
   return StepActions(IncrementalMarking::NO_GC_VIA_STACK_GUARD,
@@ skipping 1001 matching lines @@
 void IncrementalMarking::IncrementIdleMarkingDelayCounter() {
   idle_marking_delay_counter_++;
 }
 
 
 void IncrementalMarking::ClearIdleMarkingDelayCounter() {
   idle_marking_delay_counter_ = 0;
 }
 }  // namespace internal
 }  // namespace v8