Bug 650493 Part 3: Back out patch from bug 645572 as we should now always end up with correct update counts. r=ehsan

layout/base/nsCSSFrameConstructor.cpp

@@ -8284,10 +8284,8 @@ nsCSSFrameConstructor::EndUpdate()
     RecalcQuotesAndCounters();
     NS_ASSERTION(mUpdateCount == 1, "Odd update count");
   }
-  // Negative update counts don't make sense
-  if (mUpdateCount > 0) {
-    --mUpdateCount;
-  }
+  NS_ASSERTION(mUpdateCount, "Negative mUpdateCount!");
+  --mUpdateCount;
 }
 
 void