Bug 1579858 - Should release RefPtr before CollectData is clear; r=sm…

…aug a=RyanVM

mAboutToBeNotifiedRejectedPromises will be clear in AfterProcessMicrotasks()
and mPendingUnhandledRejections will be clear after NotifyUnhandledRejections
runnable is handled.

However, worker could terminate in any time, we still need to clear those
structures manually before CollectData is clear.

Differential Revision: https://phabricator.services.mozilla.com/D46095

--HG--
extra : source : 9596d7f4a7457bccc78cadf9c39bcc9c4b5b97f8
extra : intermediate-source : fffca6c7380a0e0e412887d596349df5e9e19460

xpcom/base/CycleCollectedJSContext.cpp

@@ -102,6 +102,9 @@ CycleCollectedJSContext::~CycleCollectedJSContext() {
   mUncaughtRejections.reset();
   mConsumedRejections.reset();
 
+  mAboutToBeNotifiedRejectedPromises.Clear();
+  mPendingUnhandledRejections.Clear();
+
   JS_DestroyContext(mJSContext);
   mJSContext = nullptr;