Refactor of various layout tests to use RAF

LayoutTests/svg/custom/use-detach.svg

Index: LayoutTests/svg/custom/use-detach.svg
diff --git a/LayoutTests/svg/custom/use-detach.svg b/LayoutTests/svg/custom/use-detach.svg
index a1f975baf243c7e6f55a7062a3bde9441ccf6194..213b72476eae184b7055bb122fb7c13500d4c880 100644
--- a/LayoutTests/svg/custom/use-detach.svg
+++ b/LayoutTests/svg/custom/use-detach.svg
@@ -8,12 +8,15 @@
     function repaintTest() {
       var elem = document.getElementById('use');
       elem.setAttributeNS(null,'display','inline');
-      window.setTimeout("step2()", 0);
+      // Nested RAF to ensure enough time elapsed for repaint logging to occur
+      requestAnimationFrame(function() {
+        requestAnimationFrame(step2);
+      });
     }
     function step2() {
       var elem = document.getElementById('use');
       elem.setAttributeNS(null,'display','none');
-      window.setTimeout("step3()", 0);
+      requestAnimationFrame(step3);
     }
     function step3() {
       var elem = document.getElementById('use');