Animation: Add optional specified animation id

See http://w3c.github.io/web-animations/#dom-animation-id for spec

Review URL: https://codereview.chromium.org/1695633002

Cr-Commit-Position: refs/heads/master@{#376387}

front_end/animation/AnimationModel.js

@@ -264,7 +264,7 @@ WebInspector.AnimationModel.Animation.prototype = {
      */
     name: function()
     {
-        return this.source().name();
+        return this._payload.name;
     },
 
     /**
@@ -513,14 +513,6 @@ WebInspector.AnimationModel.AnimationEffect.prototype = {
         return this._payload.fill;
     },
 
-    /**
-     * @return {string}
-     */
-    name: function()
-    {
-        return this._payload.name;
-    },
-
     /**
      * @return {!Promise.<!WebInspector.DOMNode>}
      */

protocol.json

@@ -5025,6 +5025,7 @@
                 "hidden": true,
                 "properties": [
                     { "name": "id", "type": "string", "description": "<code>Animation</code>'s id." },
+                    { "name": "name", "type": "string", "description": "<code>Animation</code>'s name." },
                     { "name": "pausedState", "type": "boolean", "hidden": "true", "description": "<code>Animation</code>'s internal paused state." },
                     { "name": "playState", "type": "string", "description": "<code>Animation</code>'s play state." },
                     { "name": "playbackRate", "type": "number", "description": "<code>Animation</code>'s playback rate." },
@@ -5049,7 +5050,6 @@
                     { "name": "duration", "type": "number", "description": "<code>AnimationEffect</code>'s iteration duration." },
                     { "name": "direction", "type": "string", "description": "<code>AnimationEffect</code>'s playback direction." },
                     { "name": "fill", "type": "string", "description": "<code>AnimationEffect</code>'s fill mode." },
-                    { "name": "name", "type": "string", "description": "<code>AnimationEffect</code>'s name." },
                     { "name": "backendNodeId", "$ref": "DOM.BackendNodeId", "description": "<code>AnimationEffect</code>'s target node." },
                     { "name": "keyframesRule", "$ref": "KeyframesRule", "optional": true, "description": "<code>AnimationEffect</code>'s keyframes." },
                     { "name": "easing", "type": "string", "description": "<code>AnimationEffect</code>'s timing function." }