DevTools: do not use Internals for inspector highlight tests.

Source/devtools/protocol.json

 {
     "version": { "major": "1", "minor": "1" },
     "domains": [{
         "domain": "Inspector",
         "hidden": true,
         "types": [],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables inspector domain notifications."
@@ skipping 2629 matching lines @@
             {
                 "name": "getRelayoutBoundary",
                 "parameters": [
                     { "name": "nodeId", "$ref": "NodeId", "description": "Id of the node." }
                 ],
                 "returns": [
                     { "name": "nodeId", "$ref": "NodeId", "description": "Relayout boundary node id for the given node." }
                 ],
                 "description": "Returns the id of the nearest ancestor that is a relayout boundary.",
                 "hidden": true
+            },
+            {
+                "name": "getHighlightObjectForTest",
+                "parameters": [
+                    { "name": "nodeId", "$ref": "NodeId", "description": "Id of the node to get highlight object for." }
+                ],
+                "returns": [
+                    { "name": "highlight", "type": "object", "description": "Highlight data for the node." }
+                ],
+                "description": "For testing.",
+                "hidden": true
             }
         ],
         "events": [
             {
                 "name": "documentUpdated",
                 "description": "Fired when <code>Document</code> has been totally updated. Node ids are no longer valid."
             },
             {
                 "name": "inspectNodeRequested",
                 "parameters": [
@@ skipping 2155 matching lines @@
             {
                 "name": "animationPlayerCreated",
                 "parameters": [
                     { "name": "player", "$ref": "AnimationPlayer", "description": "AnimationPlayer that was created." }
                 ],
                 "hidden": true
             }
         ]
     }]
 }