Disable InstanceOfStubWriteBarrier in some cases.

This disables the above regression test when run with forced marking
deque overflows (which is implicitly enabled by --stress-compaction).

R=verwaest@chromium.org
TEST=cctest/test-heap/InstanceOfStubWriteBarrier

Review URL: https://codereview.chromium.org/11417026

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12984 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

test/cctest/test-heap.cc

@@ -1733,6 +1733,7 @@ TEST(InstanceOfStubWriteBarrier) {
 
   InitializeVM();
   if (!i::V8::UseCrankshaft()) return;
+  if (i::FLAG_force_marking_deque_overflows) return;
   v8::HandleScope outer_scope;
 
   {