Bug 1052240 - Fix test failures. - r=kamidphish

dom/canvas/test/webgl-conformance/conformance/textures/texture-npot-video.html

@@ -124,8 +124,13 @@ function runOneIteration(videoElement, useTexSubImage2D, flipY, topColor, bottom
     debug("");
 }
 
+alreadyDone = false;
 function runTest(videoElement)
 {
+    if (alreadyDone)
+        return;
+    alreadyDone = true;
+
     var red = [255, 0, 0];
     var green = [0, 255, 0];
     var black = [0, 0, 0];