[heap] Color object black on unsafe layout change.

src/heap/concurrent-marking-deque.h

 // Copyright 2017 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_CONCURRENT_MARKING_DEQUE_
 #define V8_HEAP_CONCURRENT_MARKING_DEQUE_
 
 #include <deque>
 
 #include "src/base/platform/mutex.h"
@@ skipping 29 matching lines @@
  public:
   // The heap parameter is needed to match the interface
   // of the sequential marking deque.
   explicit ConcurrentMarkingDeque(Heap* heap) {}
 
   // Pushes the object into the specified deque assuming that the function is
   // called on the specified thread. The main thread can push only to the shared
   // deque. The concurrent thread can push to both deques.
   bool Push(HeapObject* object, MarkingThread thread = MarkingThread::kMain,
             TargetDeque target = TargetDeque::kShared) {
-    DCHECK_IMPLIES(thread == MarkingThread::kMain,
-                   target == TargetDeque::kShared);
     switch (target) {
       case TargetDeque::kShared:
         shared_deque_.Push(object);
         break;
       case TargetDeque::kBailout:
         bailout_deque_.Push(object);
         break;
     }
     return true;
   }
@@ skipping 106 matching lines @@
   };
   Deque bailout_deque_;
   Deque shared_deque_;
   DISALLOW_COPY_AND_ASSIGN(ConcurrentMarkingDeque);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CONCURRENT_MARKING_DEQUE_