Rewrite svg/dynamic-updates to use text-based repaint harness

LayoutTests/fast/repaint/resources/text-based-repaint.js

 function runRepaintTest()
 {
     if (window.testRunner && window.internals) {
-        window.testRunner.dumpAsText();
+        if (window.enablePixelTesting)
+            window.testRunner.dumpAsTextWithPixelResults();
+        else
+            window.testRunner.dumpAsText();
 
         if (document.body)
             document.body.offsetTop;
         else if (document.documentElement)
             document.documentElement.offsetTop;
 
         window.internals.startTrackingRepaints(document);
 
         repaintTest();
 
         // force a style recalc.
         var dummy = document.body.offsetTop;
 
         var repaintRects = window.internals.repaintRectsAsText(document);
 
         window.internals.stopTrackingRepaints(document);
 
         var pre = document.createElement('pre');
         document.body.appendChild(pre);
-        pre.innerHTML = repaintRects;
+        pre.textContent += repaintRects;
+
+        if (window.afterTest)
+            window.afterTest();
     } else {
         setTimeout(repaintTest, 100);
     }
 }