PerformanceMonitor: do not leak performance objects through the monitor.

third_party/WebKit/Source/core/timing/Performance.cpp

Index: third_party/WebKit/Source/core/timing/Performance.cpp
diff --git a/third_party/WebKit/Source/core/timing/Performance.cpp b/third_party/WebKit/Source/core/timing/Performance.cpp
index 0a6f2c9b45f4aa8ad9be010818929de0c224a6fb..2bf1572d39744af76477cc2abd9896f37417d6d7 100644
--- a/third_party/WebKit/Source/core/timing/Performance.cpp
+++ b/third_party/WebKit/Source/core/timing/Performance.cpp
@@ -61,7 +61,13 @@ Performance::Performance(LocalFrame* frame)
     : PerformanceBase(toTimeOrigin(frame)), DOMWindowProperty(frame) {}
 
 Performance::~Performance() {
+  if (frame())
+    PerformanceMonitor::performanceObserverRemoved(this);
+}
+
+void Performance::frameDestroyed() {
   PerformanceMonitor::performanceObserverRemoved(this);
+  DOMWindowProperty::frameDestroyed();
 }
 
 ExecutionContext* Performance::getExecutionContext() const {