Explicit notification and removal of lifecycle observers.

Source/core/dom/ExecutionContext.cpp

Index: Source/core/dom/ExecutionContext.cpp
diff --git a/Source/core/dom/ExecutionContext.cpp b/Source/core/dom/ExecutionContext.cpp
index a0b89148f4c2026c95172ba8a3147e3d5bd579ce..ac0de7b0564eae0a414be21b1d900fe7f3a9ed96 100644
--- a/Source/core/dom/ExecutionContext.cpp
+++ b/Source/core/dom/ExecutionContext.cpp
@@ -96,6 +96,11 @@ void ExecutionContext::stopActiveDOMObjects()
     lifecycleNotifier().notifyStoppingActiveDOMObjects();
 }
 
+void ExecutionContext::removeAllLifecycleObservers()
+{
+    lifecycleNotifier().removeAndNotifyAllObservers();
+}
+
 unsigned ExecutionContext::activeDOMObjectCount()
 {
     return lifecycleNotifier().activeDOMObjects().size();