DevTools: beautify the responsive design warning message.

Source/devtools/front_end/ResponsiveDesignView.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @constructor
  * @extends {WebInspector.VBox}
  * @implements {WebInspector.OverridesSupport.PageResizer}
  * @param {!WebInspector.InspectedPagePlaceholder} inspectedPagePlaceholder
  */
 WebInspector.ResponsiveDesignView = function(inspectedPagePlaceholder)
 {
     WebInspector.VBox.call(this);
     this.setMinimumSize(150, 150);
     this.registerRequiredCSS("responsiveDesignView.css");
     this.element.classList.add("overflow-hidden");
 
     this._responsiveDesignContainer = new WebInspector.VBox();
 
     this._createToolbar();
 
     this._canvasContainer = new WebInspector.View();
     this._canvasContainer.element.classList.add("responsive-design");
     this._canvasContainer.show(this._responsiveDesignContainer.element);
 
     this._canvas = this._canvasContainer.element.createChild("canvas", "fill");
 
     this._warningMessage = this._canvasContainer.element.createChild("div", "responsive-design-warning hidden");
+    this._warningMessage.createChild("div", "warning-icon-small");
     this._warningMessage.createChild("span");
-    var warningCloseButton = this._warningMessage.createChild("div", "responsive-design-warning-close");
+    var warningCloseButton = this._warningMessage.createChild("div", "close-button");
     warningCloseButton.addEventListener("click", this._closeOverridesWarning.bind(this), false);
     WebInspector.overridesSupport.addEventListener(WebInspector.OverridesSupport.Events.OverridesWarningUpdated, this._overridesWarningUpdated, this);
 
     this._slidersContainer = this._canvasContainer.element.createChild("div", "vbox responsive-design-sliders-container");
     var hbox = this._slidersContainer.createChild("div", "hbox flex-auto");
     this._heightSliderContainer = this._slidersContainer.createChild("div", "hbox responsive-design-slider-height");
     this._resolutionHeightLabel = this._heightSliderContainer.createChild("div", "responsive-design-resolution-label responsive-design-resolution-height");
     this._pageContainer = hbox.createChild("div", "vbox flex-auto");
     this._widthSliderContainer = hbox.createChild("div", "vbox responsive-design-slider-width");
     this._resolutionWidthLabel = this._widthSliderContainer.createChild("div", "responsive-design-resolution-label responsive-design-resolution-width");
@@ skipping 475 matching lines @@
     },
 
     _closeOverridesWarning: function()
     {
         this._warningMessage.querySelector("span").textContent = "";
         this._warningMessage.classList.add("hidden");
     },
 
     __proto__: WebInspector.VBox.prototype
 };