[DevTools] Replace usages of document with custom functions.

Source/devtools/front_end/components/ShortcutsScreen.js

Index: Source/devtools/front_end/components/ShortcutsScreen.js
diff --git a/Source/devtools/front_end/components/ShortcutsScreen.js b/Source/devtools/front_end/components/ShortcutsScreen.js
index 30972b6f9736a5ca6c190b92f3ee72ae3b537800..0184136bd719f3a5cf0b3259623b23681d78aea5 100644
--- a/Source/devtools/front_end/components/ShortcutsScreen.js
+++ b/Source/devtools/front_end/components/ShortcutsScreen.js
@@ -189,7 +189,7 @@ WebInspector.ShortcutsSection.prototype = {
      */
     _createSpan: function(className, textContent)
     {
-        var node = document.createElement("span");
+        var node = createElement("span");
         node.className = className;
         node.textContent = textContent;
         return node;
@@ -202,7 +202,7 @@ WebInspector.ShortcutsSection.prototype = {
      */
     _joinNodes: function(nodes, delimiter)
     {
-        var result = document.createDocumentFragment();
+        var result = createDocumentFragment();
         for (var i = 0; i < nodes.length; ++i) {
             if (i > 0)
                 result.appendChild(delimiter.cloneNode(true));