Make incremental marking tracing format consistent with GC tracing.

src/heap/incremental-marking-inl.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_HEAP_INCREMENTAL_MARKING_INL_H_
 #define V8_HEAP_INCREMENTAL_MARKING_INL_H_
 
 #include "src/heap/incremental-marking.h"
+#include "src/isolate.h"
 
 namespace v8 {
 namespace internal {
 
 
 void IncrementalMarking::RecordWrite(HeapObject* obj, Object** slot,
                                      Object* value) {
   if (IsMarking() && value->IsHeapObject()) {
     RecordWriteSlow(obj, slot, value);
   }
 }
 
 
 void IncrementalMarking::RecordWriteOfCodeEntry(JSFunction* host, Object** slot,
                                                 Code* value) {
   if (IsMarking()) {
     RecordWriteOfCodeEntrySlow(host, slot, value);
   }
 }
 
 void IncrementalMarking::RecordWriteIntoCode(Code* host, RelocInfo* rinfo,
                                              Object* value) {
   if (IsMarking() && value->IsHeapObject()) {
     RecordWriteIntoCodeSlow(host, rinfo, value);
   }
 }
 
+void IncrementalMarking::RestartIfNotMarking() {
+  if (state_ == COMPLETE) {
+    state_ = MARKING;
+    if (FLAG_trace_incremental_marking) {
+      heap()->isolate()->PrintWithTimestamp(
+          "[IncrementalMarking] Restarting (new grey objects)\n");
+    }
+  }
+}
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_INCREMENTAL_MARKING_INL_H_