Bug 1211647 - Runtime graphics testing visible during session restore. r=mchang

MozReview-Commit-ID: 46Bi2eW5NB5

--HG--
extra : amend_source : 33fa624f98cac2a888ab7dca3207beb2f35c99d0
extra : transplant_source : %FE%E24%EAm%BC%22%F97%7B%3B%F6%BA%E7%F7%04%07x%BF%86

toolkit/components/gfx/SanityTest.js

@@ -304,7 +304,7 @@ SanityTest.prototype = {
     var sanityTest = Services.ww.openWindow(null,
         "chrome://gfxsanity/content/sanityparent.html",
         "Test Page",
-        "width=" + PAGE_WIDTH + ",height=" + PAGE_HEIGHT + ",chrome,titlebar=0,scrollbars=0",
+        "width=" + PAGE_WIDTH + ",height=" + PAGE_HEIGHT + ",chrome,titlebar=0,scrollbars=0,popup=1",
         null);
 
     // There's no clean way to have an invisible window and ensure it's always painted.