[Shadow DOM]: Empty shadow insertion points should behave like <shadow><content *leftover*></conten…

LayoutTests/fast/dom/shadow/resources/event-dispatching.js

 description("Tests to ensure that event dispatching behaves as the Shadow DOM spec describes.");
 
 var defaultPaddingSize = 40;
 
 function moveMouseOver(element)
 {
     if (!window.eventSender || !window.internals)
         return;
 
     var x = element.offsetLeft + element.offsetWidth / 2;
@@ skipping 153 matching lines @@
     debug('\n' + 'Moving mouse from ' + oldElementId + ' to ' + newElementId);
     moveMouseOver(getNodeInTreeOfTrees(oldElementId));
 
     clearEventRecords();
     moveMouseOver(getNodeInTreeOfTrees(newElementId));
 
     debugDispatchedEvent('mouseout');
     debugDispatchedEvent('mouseover');
 }
 
+function clickElement(elementId)
+{
+    clearEventRecords();
+    debug('\n' + 'Click ' + elementId);
+    var clickEvent = document.createEvent("MouseEvents");
+    clickEvent.initMouseEvent('click', true, false, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
+    getNodeInTreeOfTrees(elementId).dispatchEvent(clickEvent);
+    debugDispatchedEvent('click');
+}
+
 function showSandboxTree()
 {
     var sandbox = document.getElementById('sandbox');
     sandbox.offsetLeft;
     debug('\n\nComposed Shadow Tree will be:\n' + dumpComposedShadowTree(sandbox));
 }