Bug 1112920 - Assert against pending exceptions in AutoJSAPI::InitInternal. v1 r=luke,r=smaug

dom/base/ScriptSettings.cpp

@@ -334,6 +334,7 @@ AutoJSAPI::InitInternal(JSObject* aGlobal, JSContext* aCx, bool aIsMainThread)
 {
   MOZ_ASSERT(aCx);
   MOZ_ASSERT(aIsMainThread == NS_IsMainThread());
+  MOZ_ASSERT(!JS_IsExceptionPending(mCx));
 
   mCx = aCx;
   mIsMainThread = aIsMainThread;