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

LayoutTests/svg/dynamic-updates/resources/SVGTestCase.js

 // Force activating pixel tests - this variable is used in resources/js-test.js, when calling setDumpAsText().
 window.enablePixelTesting = true;
 
 var svgNS = "http://www.w3.org/2000/svg";
 var xlinkNS = "http://www.w3.org/1999/xlink";
 var xhtmlNS = "http://www.w3.org/1999/xhtml";
 
 var rootSVGElement;
 var iframeElement;
 
+if (window.testRunner) {
+    var s = document.createElement('style');
+    s.innerHTML += ".running h1, .running pre, .running div#console, .running p { display:none }";
+    s.innerHTML += "h1, pre, div#console, p { opacity: 0 }";
+    s.innerHTML += "body { overflow: hidden }";
+    document.head.appendChild(s);
+    document.head.parentNode.classList.add("running");
+}
+
+function afterTest() {
+    document.head.parentNode.classList.remove("running");
+}
+
 function createSVGElement(name) {
     return document.createElementNS(svgNS, "svg:" + name);
 }
 
 function shouldHaveBBox(element, width, height)
 {
     shouldBe(element + ".getBBox().width", width);
     shouldBe(element + ".getBBox().height", height);
 }
 
@@ skipping 36 matching lines @@
     if (window.eventSender) {
         eventSender.mouseMoveTo(x, y);
         eventSender.mouseDown();
         eventSender.mouseUp();
     }
 }
 
 function completeTest() {
     finishJSTest();
 }