Do not implement EventTarget on SVGElementInstance

LayoutTests/svg/custom/resources/use-instanceRoot-event-listeners.js

 var counter = 0;
 var tests = 8;
 var expected = "";
 var logEvent = false;
 var rectElement = document.getElementById("target");
 var useElement = document.getElementById("test");
 window.testIsAsync = true;
 description("Test attaching event listeners on SVG use elements in different ways: ");
 
 function eventHandler(evt)
 {
     if (logEvent) {
         if (expected == evt.type)
             debug("Test " + counter + " / " + tests + " PASSED");
         else
             debug("Test " + counter + " / " + tests + " FAILED (expected: '" + expected + "' actual: '" + evt.type + "')");
     }
 
     setTimeout(counter < tests ? driveTests : finishTest, 0);
 }
 
 function finishTest()
 {
     successfullyParsed = true;
 
-    useElement.instanceRoot.correspondingElement.setAttribute("fill", "green");
+    rectElement.setAttribute("fill", "green");
     shouldBeTrue("successfullyParsed");
     debug('<br /><span class="pass">TEST COMPLETE</span>');
 
     finishRepaintTest();
 }
 
 function recordMouseEvent(type)
 {
     expected = type;
     logEvent = true;
@@ skipping 22 matching lines @@
     } else if (expected == "mousedown") {
         eventSender.mouseMoveTo(50, 50);
         eventSender.mouseDown();
         eventSender.mouseUp();
     }
 }
 
 function testOne()
 {
     // Install event listener on correspondingElement via setAttribute
-    useElement.instanceRoot.correspondingElement.setAttribute("onmouseover", "eventHandler(evt)");
+    shadowRoot.firstChild.setAttribute("onmouseover", "eventHandler(evt)");
     recordMouseEvent("mouseover");
 }
 
 function testTwo()
 {
     // Install event listener on correspondingElement via onmouseout JS magic
-    useElement.instanceRoot.correspondingElement.onmouseout = eventHandler;
+    shadowRoot.firstChild.onmouseout = eventHandler;
     recordMouseEvent("mouseout");
 }
 
 function testThree()
 {
     // Clean event listeners on different ways
-    useElement.instanceRoot.correspondingElement.removeAttribute("onmouseover");
-    useElement.instanceRoot.correspondingElement.onmouseout = 0;
+    shadowRoot.firstChild.removeAttribute("onmouseover");
+    shadowRoot.firstChild.onmouseout = 0;
 
     // Verify they really got removed
     sendMouseEvent("mouseover");
     sendMouseEvent("mouseout");
 
     // Verify the original listener still works
     recordMouseEvent("mousedown");
 }
 
 function testFour()
 {
-    useElement.instanceRoot.correspondingElement.removeAttribute("onmousedown");
+    shadowRoot.firstChild.removeAttribute("onmousedown");
 
     // Install event listener on the referenced element, without using the SVGElementInstance interface
     rectElement.setAttribute("onmouseup", "eventHandler(evt)");
     recordMouseEvent("mouseup");
 }
 
 function testFive()
 {
     rectElement.onmouseout = eventHandler;
     recordMouseEvent("mouseout");
 }
 
 function testSix()
 {
-    useElement.instanceRoot.correspondingElement.onmouseout = null;
+    shadowRoot.firstChild.onmouseout = null;
     sendMouseEvent("mouseout");
 
-    useElement.instanceRoot.correspondingElement.removeAttribute('onmouseup');
+    shadowRoot.firstChild.removeAttribute('onmouseup');
     sendMouseEvent("mouseup");
 
-    useElement.instanceRoot.correspondingElement.onmouseup = eventHandler;
+    shadowRoot.firstChild.onmouseup = eventHandler;
     recordMouseEvent("mouseup");
 }
 
 function testSeven()
 {
-    useElement.instanceRoot.addEventListener("mouseout", eventHandler, false);
+    shadowRoot.firstChild.addEventListener("mouseout", eventHandler, false);
     recordMouseEvent("mouseout");
 }
 
 function testEight()
 {
-    useElement.instanceRoot.correspondingElement.addEventListener("mouseover", eventHandler, false);
+    shadowRoot.firstChild.addEventListener("mouseover", eventHandler, false);
     recordMouseEvent("mouseover");
 }
 
 function testNine()
 {
     rectElement.addEventListener("mousedown", eventHandler, false);
     recordMouseEvent("mousedown");
 }
 
 function driveTests()
@@ skipping 25 matching lines @@
         break;
     }
 }
 
 function repaintTest() {
     if (window.eventSender)
         driveTests();
     else
         alert("This test must be run via DRT!");
 }