Bug 806433 - Make mReleaseRunnable a ref ptr. r=smaug

js/xpconnect/src/XPCJSRuntime.cpp

@@ -2362,7 +2362,6 @@ XPCJSRuntime::XPCJSRuntime(nsXPConnect* aXPConnect)
    mWatchdogThread(nullptr),
    mWatchdogHibernating(false),
    mLastActiveTime(-1),
-   mReleaseRunnable(nullptr),
    mExceptionManagerNotAvailable(false)
 {
 #ifdef XPC_CHECK_WRAPPERS_AT_SHUTDOWN

js/xpconnect/src/xpcprivate.h

@@ -965,7 +965,7 @@ private:
     nsTArray<JSGCCallback> extraGCCallbacks;
     bool mWatchdogHibernating;
     PRTime mLastActiveTime; // -1 if active NOW
-    XPCIncrementalReleaseRunnable *mReleaseRunnable;
+    nsRefPtr<XPCIncrementalReleaseRunnable> mReleaseRunnable;
     js::GCSliceCallback mPrevGCSliceCallback;
 
     nsCOMPtr<nsIException>   mPendingException;