Synchronous image loading for opacity and backbuffer tests

tests/Layer/Grid.html

@@ -770,7 +770,9 @@
     }
 
     function test_setOpacity(t) {
-
+        var origRequestFrame = OpenLayers.Animation.requestFrame;
+        OpenLayers.Animation.requestFrame = function(fn) { fn(); };
+        
         t.plan(5);
 
         var map = new OpenLayers.Map('map');
@@ -799,6 +801,8 @@
         t.eq(parseFloat(tile.imgDiv.style.opacity), 0.2, "tile opacity is correc");
 
         map.destroy();
+        
+        OpenLayers.Animation.requestFrame = origRequestFrame
     }
     
     function test_getServerResolution(t) {
@@ -1309,6 +1313,8 @@
     }
 
     function test_delayed_back_buffer_removal(t) {
+        var origRequestFrame = OpenLayers.Animation.requestFrame;
+        OpenLayers.Animation.requestFrame = function(fn) { fn(); };
 
         //
         // Test that the delaying of the back buffer removal behaves
@@ -1353,6 +1359,8 @@
         // tear down
 
         map.destroy();
+        
+        OpenLayers.Animation.requestFrame = origRequestFrame;
     }
     
     function test_getGridData(t) {