See if using mScanDelay of 1 instead of 0 fixes the leak regression.

xpcom/base/nsCycleCollector.cpp

@@ -195,7 +195,7 @@ struct nsCycleCollectorParams
         //   - More time to be spent in the collector (bad)
         //   - Less delay between forming garbage and collecting it (good)
 
-        mScanDelay(0)
+        mScanDelay(1)
     {
 #ifdef DEBUG_CC
         char *s = PR_GetEnv("XPCOM_CC_SCAN_DELAY");