[DevTools] Replace usages of document with custom functions.

Source/devtools/front_end/source_frame/FontView.js

 /*
  * Copyright (C) 2007, 2008 Apple 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 35 matching lines @@
 WebInspector.FontView._measureFontSize = 50;
 
 WebInspector.FontView.prototype = {
     _createContentIfNeeded: function()
     {
         if (this.fontPreviewElement)
             return;
 
         var uniqueFontName = "WebInspectorFontPreview" + (++WebInspector.FontView._fontId);
 
-        this.fontStyleElement = document.createElement("style");
+        this.fontStyleElement = createElement("style");
         this.fontStyleElement.textContent = "@font-face { font-family: \"" + uniqueFontName + "\"; src: url(" + this._url + "); }";
         document.head.appendChild(this.fontStyleElement);
 
-        var fontPreview = document.createElement("div");
+        var fontPreview = createElement("div");
         for (var i = 0; i < WebInspector.FontView._fontPreviewLines.length; ++i) {
             if (i > 0)
                 fontPreview.createChild("br");
             fontPreview.createTextChild(WebInspector.FontView._fontPreviewLines[i]);
         }
         this.fontPreviewElement = fontPreview.cloneNode(true);
         this.fontPreviewElement.style.setProperty("font-family", uniqueFontName);
         this.fontPreviewElement.style.setProperty("visibility", "hidden");
 
         this._dummyElement = fontPreview;
@@ skipping 58 matching lines @@
 
         var widthRatio = containerWidth / width;
         var heightRatio = containerHeight / height;
         var finalFontSize = Math.floor(WebInspector.FontView._measureFontSize * Math.min(widthRatio, heightRatio)) - 2;
 
         this.fontPreviewElement.style.setProperty("font-size", finalFontSize + "px", null);
     },
 
     __proto__: WebInspector.VBox.prototype
 }