[DevTools] Consolidate overlay-related functionality in Overlay domain

third_party/WebKit/LayoutTests/http/tests/inspector/elements-test.js

 var initialize_ElementTest = function() {
 
 InspectorTest.preloadPanel("elements");
 
 InspectorTest.inlineStyleSection = function()
 {
     return UI.panels.elements._stylesWidget._sectionBlocks[0].sections[0];
 }
 
 InspectorTest.computedStyleWidget = function()
@@ skipping 949 matching lines @@
     section._selectorElement.dispatchEvent(InspectorTest.createKeyEvent("Enter"));
     InspectorTest.waitForSelectorCommitted(callback.bind(null, section));
 }
 
 InspectorTest.dumpInspectorHighlightJSON = function(idValue, callback)
 {
     InspectorTest.nodeWithId(idValue, nodeResolved);
 
     function nodeResolved(node)
     {
-        InspectorTest.DOMAgent.getHighlightObjectForTest(node.id, report);
+        InspectorTest.OverlayAgent.getHighlightObjectForTest(node.id, report);
     }
 
     function report(error, result)
     {
         InspectorTest.addResult(idValue + JSON.stringify(result, null, 2));
         callback();
     }
 }
 
 InspectorTest.waitForAnimationAdded = function(callback)
 {
     InspectorTest.addSniffer(Animation.AnimationTimeline.prototype, "_addAnimationGroup", callback);
 }
 
 InspectorTest.dumpAnimationTimeline = function(timeline)
 {
     for (var ui of timeline._uiAnimations) {
         InspectorTest.addResult(ui.animation().type());
         InspectorTest.addResult(ui._nameElement.innerHTML);
         InspectorTest.addResult(ui._svg.innerHTML);
     }
 }
 
 };