Bug 485841 - Get rid of some timeouts and avoid boxObject where appropriate in tabbrowser, part 3. r=enn

browser/base/content/tabbrowser.xml

@@ -2992,10 +2992,7 @@
             this.setAttribute("closebuttons", "activetab");
             break;
           case 1:
-            var width = this.firstChild.boxObject.width;
-            // 0 width is an invalid value and indicates
-            // an item without display, so ignore.
-            if (width > this.mTabClipWidth || width == 0)
+            if (this.firstChild.clientWidth > this.mTabClipWidth)
               this.setAttribute("closebuttons", "alltabs");
             else
               this.setAttribute("closebuttons", "activetab");