DevTools: Split creating inspector stylesheet and adding a new rule into stylesheet in protocol.

Source/devtools/front_end/DOMAgent.js

Index: Source/devtools/front_end/DOMAgent.js
diff --git a/Source/devtools/front_end/DOMAgent.js b/Source/devtools/front_end/DOMAgent.js
index 9e4a4fbc0e798309a8597db0cd4333aad2acf490..45a624a87212fa88668abb6770deb0cf6e8c6eb5 100644
--- a/Source/devtools/front_end/DOMAgent.js
+++ b/Source/devtools/front_end/DOMAgent.js
@@ -49,6 +49,7 @@ WebInspector.DOMNode = function(domAgent, doc, isInShadowTree, payload) {
     this._nodeValue = payload.nodeValue;
     this._pseudoType = payload.pseudoType;
     this._shadowRootType = payload.shadowRootType;
+    this._frameId = payload.frameId || null;
 
     this._shadowRoots = [];
 
@@ -475,6 +476,17 @@ WebInspector.DOMNode.prototype = {
     },
 
     /**
+     * @return {?PageAgent.FrameId}
+     */
+    frameId: function()
+    {
+        var node = this;
+        while (!node._frameId && node.parentNode)
+            node = node.parentNode;
+        return node._frameId;
+    },
+
+    /**
      * @param {!Array.<string>} attrs
      * @return {boolean}
      */