Bug 1400337 - only set 'progress' attribute if 'busy' is already set, r=jaws

MozReview-Commit-ID: Ivumb7ze69A

--HG--
extra : rebase_source : 3231f7651a94a0a896560b981701f69bbbb88bd2

browser/base/content/tabbrowser.xml

@@ -669,7 +669,7 @@
               if (!this._shouldShowProgress(aRequest))
                 return;
 
-              if (this.mTotalProgress && aWebProgress && aWebProgress.isTopLevel)
+              if (this.mTotalProgress && this.mTab.hasAttribute("busy"))
                 this.mTab.setAttribute("progress", "true");
 
               this._callProgressListeners("onProgressChange",