[wrapper-tracing] Enable cleanup and invalidating on WorkerBackingThread

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

Index: third_party/WebKit/Source/platform/heap/ThreadState.h
diff --git a/third_party/WebKit/Source/platform/heap/ThreadState.h b/third_party/WebKit/Source/platform/heap/ThreadState.h
index 09d6860c233ee2ad5affdf967f36c1f8eca47126..aafbf309c7088989073e0210016f669032b37775 100644
--- a/third_party/WebKit/Source/platform/heap/ThreadState.h
+++ b/third_party/WebKit/Source/platform/heap/ThreadState.h
@@ -437,6 +437,9 @@ class PLATFORM_EXPORT ThreadState {
       void (*invalidateDeadObjectsInWrappersMarkingDeque)(v8::Isolate*),
       void (*performCleanup)(v8::Isolate*)) {
     m_isolate = isolate;
+    DCHECK(!m_isolate || traceDOMWrappers);
+    DCHECK(!m_isolate || invalidateDeadObjectsInWrappersMarkingDeque);
+    DCHECK(!m_isolate || performCleanup);
     m_traceDOMWrappers = traceDOMWrappers;
     m_invalidateDeadObjectsInWrappersMarkingDeque =
         invalidateDeadObjectsInWrappersMarkingDeque;