Bug 781053 - Part 3 - Force the throbber into it's own layer. r=roc

browser/base/content/tabbrowser.xml

@@ -3958,7 +3958,8 @@
                   class="tab-content" align="center">
           <xul:image xbl:inherits="fadein,pinned,busy,progress,selected"
                      class="tab-throbber"
-                     role="presentation"/>
+                     role="presentation"
+                     layer="true" />
           <xul:image xbl:inherits="validate,src=image,fadein,pinned,selected"
                      class="tab-icon-image"
                      role="presentation"/>

layout/base/tests/chrome/test_leaf_layers_partition_browser_window.xul

@@ -43,7 +43,7 @@
       var initialCount = win.mozPaintCount;
 
       function nextStep() {
-        if (win.mozPaintCount == initialCount) {
+        if (win.mozPaintCount == initialCount || win.isMozAfterPaintPending) {
           SimpleTest.info("Waiting for mozPaintCount (= " + initialCount + ") to increase" + testInfo());
           // Do not use SimpleTest.executeSoon() here: give a little more time.
           setTimeout(nextStep, 100);