Enable per thread heap for database thread

third_party/WebKit/Source/platform/heap/Heap.h

Index: third_party/WebKit/Source/platform/heap/Heap.h
diff --git a/third_party/WebKit/Source/platform/heap/Heap.h b/third_party/WebKit/Source/platform/heap/Heap.h
index 40482db58d209521ff8e441509afa93a356ac2cb..13d8c977a030037ac5584c020e93915c4f671d32 100644
--- a/third_party/WebKit/Source/platform/heap/Heap.h
+++ b/third_party/WebKit/Source/platform/heap/Heap.h
@@ -202,6 +202,8 @@ public:
         // always 'alive'.
         if (!object)
             return true;
+        // TODO(keishi): some tests create CrossThreadPersistent on non attached threads.

[haraken, 2016/05/24 16:15:28]

Do you know what tests are doing that?

But conceptually, I think it is valid to create a CrossThreadPersistent on a
non-attached thread.

+        DCHECK(!ThreadState::current() || &ThreadState::current()->heap() == &pageFromObject(object)->arena()->getThreadState()->heap());
         return ObjectAliveTrait<T>::isHeapObjectAlive(object);
     }
     template<typename T>