[DevTools] Replace usages of document with custom functions.

Source/devtools/front_end/source_frame/CodeMirrorTextEditor.js

 /*
  * Copyright (C) 2012 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 677 matching lines @@
         WebInspector.CodeMirrorTextEditor._whitespaceStyleInjected = true;
         const classBase = ".show-whitespaces .CodeMirror .cm-whitespace-";
         const spaceChar = "·";
         var spaceChars = "";
         var rules = "";
         for (var i = 1; i <= WebInspector.CodeMirrorTextEditor.MaximumNumberOfWhitespacesPerSingleSpan; ++i) {
             spaceChars += spaceChar;
             var rule = classBase + i + "::before { content: '" + spaceChars + "';}\n";
             rules += rule;
         }
-        var style = document.createElement("style");
+        var style = createElement("style");
         style.textContent = rules;
         document.head.appendChild(style);
     },
 
     _handleKeyDown: function(e)
     {
         if (this._autocompleteController.keyDown(e))
             e.consume(true);
     },
 
@@ skipping 1725 matching lines @@
     function tokenOverride(superToken, stream, state)
     {
         var token = superToken(stream, state);
         return token ? tokenPrefix + token.split(/ +/).join(" " + tokenPrefix) : token;
     }
 }
 
 WebInspector.CodeMirrorTextEditor._overrideModeWithPrefixedTokens("css", "css-");
 WebInspector.CodeMirrorTextEditor._overrideModeWithPrefixedTokens("javascript", "js-");
 WebInspector.CodeMirrorTextEditor._overrideModeWithPrefixedTokens("xml", "xml-");