Bug 1021124 - Bail out of InterruptCallback if we're too early in startup. r=bz

js/xpconnect/src/XPCJSRuntime.cpp

@@ -1386,6 +1386,11 @@ XPCJSRuntime::InterruptCallback(JSContext *cx)
         return true;
     }
 
+    // Sometimes we get called back during XPConnect initialization, before Gecko
+    // has finished bootstrapping. Avoid crashing in nsContentUtils below.
+    if (!nsContentUtils::IsInitialized())
+        return true;
+
     // This is at least the second interrupt callback we've received since
     // returning to the event loop. See how long it's been, and what the limit
     // is.