[heap] Add --stress-incremental-marking flag.

test/cctest/heap/test-spaces.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 641 matching lines @@
     new_space->RemoveAllocationObserver(&observer1);
     new_space->RemoveAllocationObserver(&observer2);
 
     CHECK_EQ(observer1.count(), 32);
     CHECK_EQ(observer2.count(), 28);
   }
   isolate->Dispose();
 }
 
 TEST(ShrinkPageToHighWaterMarkFreeSpaceEnd) {
+  FLAG_stress_incremental_marking = false;
   CcTest::InitializeVM();
   Isolate* isolate = CcTest::i_isolate();
   HandleScope scope(isolate);
 
   heap::SealCurrentObjects(CcTest::heap());
 
   // Prepare page that only contains a single object and a trailing FreeSpace
   // filler.
   Handle<FixedArray> array = isolate->factory()->NewFixedArray(128, TENURED);
   Page* page = Page::FromAddress(array->address());
@@ skipping 80 matching lines @@
   HeapObject* filler =
       HeapObject::FromAddress(array->address() + array->Size());
   CHECK_EQ(filler->map(), CcTest::heap()->two_pointer_filler_map());
 
   const size_t shrinked = page->ShrinkToHighWaterMark();
   CHECK_EQ(0u, shrinked);
 }
 
 }  // namespace internal
 }  // namespace v8