[DevTools] Replace usages of document with custom functions.

Source/devtools/front_end/screencast/ScreencastView.js

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 663 matching lines @@
         this._inspectModeConfig = enabled ? config : null;
         if (callback)
             callback(null);
     },
 
     /**
      * @param {!CanvasRenderingContext2D} context
      */
     _createCheckerboardPattern: function(context)
     {
-        var pattern = /** @type {!HTMLCanvasElement} */(document.createElement("canvas"));
+        var pattern = /** @type {!HTMLCanvasElement} */(createElement("canvas"));
         const size = 32;
         pattern.width = size * 2;
         pattern.height = size * 2;
         var pctx = pattern.getContext("2d");
 
         pctx.fillStyle = "rgb(195, 195, 195)";
         pctx.fillRect(0, 0, size * 2, size * 2);
 
         pctx.fillStyle = "rgb(225, 225, 225)";
         pctx.fillRect(0, 0, size, size);
@@ skipping 161 matching lines @@
           return;
         this._maxDisplayedProgress = progress;
         this._displayProgress(progress);
     },
 
     _displayProgress: function(progress)
     {
         this._element.style.width = (100 * progress) + "%";
     }
 };