Bug 1115812 patch 20 - Add assertions that mDoRebuildAllStyleData and mInRebuildAllStyleData are false by the end of restyle processing. r=heycam

These assertions are as requested in comment 30 in the bug.

(If the first one doesn't fire, it's possible we could even get rid of
the handling of mDoRebuildAllStyleData that it's within.)

layout/base/RestyleManager.cpp

@@ -1651,7 +1651,13 @@ RestyleManager::ProcessPendingRestyles()
     // and it should be rarely used.
     // This might add us as a refresh observer again; that's ok.
     ProcessPendingRestyles();
+
+    NS_ASSERTION(!mDoRebuildAllStyleData,
+                 "repeatedly setting mDoRebuildAllStyleData?");
   }
+
+  MOZ_ASSERT(!mInRebuildAllStyleData,
+             "should have called FinishRebuildAllStyleData");
 }
 
 void