[heap] Minor MC: Add marking

test/cctest/test-weakmaps.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 231 matching lines @@
   // Force compacting garbage collection. The subsequent collections are used
   // to verify that key references were actually updated.
   CHECK(FLAG_always_compact);
   CcTest::CollectAllGarbage(i::Heap::kFinalizeIncrementalMarkingMask);
   CcTest::CollectAllGarbage(i::Heap::kFinalizeIncrementalMarkingMask);
   CcTest::CollectAllGarbage(i::Heap::kFinalizeIncrementalMarkingMask);
 }
 
 
 TEST(Regress399527) {
+  if (!FLAG_incremental_marking) return;
   CcTest::InitializeVM();
   v8::HandleScope scope(CcTest::isolate());
   Isolate* isolate = CcTest::i_isolate();
   Heap* heap = isolate->heap();
   {
     HandleScope scope(isolate);
     AllocateJSWeakMap(isolate);
     heap::SimulateIncrementalMarking(heap);
   }
   // The weak map is marked black here but leaving the handle scope will make
   // the object unreachable. Aborting incremental marking will clear all the
   // marking bits which makes the weak map garbage.
   CcTest::CollectAllGarbage(i::Heap::kFinalizeIncrementalMarkingMask);
 }