DevTools: Reduce code via using document.createElementWithClass and document.createChild.

Source/devtools/front_end/source_frame/SourceFrame.js

 /*
  * Copyright (C) 2011 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 642 matching lines @@
                 return;
             }
         }
 
         var rowMessage = { consoleMessage: msg };
         rowMessages.push(rowMessage);
 
         this._textEditor.beginUpdates();
         var messageBubbleElement = this._messageBubbles[lineNumber];
         if (!messageBubbleElement) {
-            messageBubbleElement = document.createElement("div");
-            messageBubbleElement.className = "webkit-html-message-bubble";
+            messageBubbleElement = document.createElementWithClass("div", "webkit-html-message-bubble");
             this._messageBubbles[lineNumber] = messageBubbleElement;
             this._textEditor.addDecoration(lineNumber, messageBubbleElement);
         }
 
         var imageElement = document.createElement("div");
         switch (msg.level) {
             case WebInspector.ConsoleMessage.MessageLevel.Error:
                 messageBubbleElement.classList.add("webkit-html-error-message");
                 imageElement.className = "error-icon-small";
                 break;
             case WebInspector.ConsoleMessage.MessageLevel.Warning:
                 messageBubbleElement.classList.add("webkit-html-warning-message");
                 imageElement.className = "warning-icon-small";
                 break;
         }
 
-        var messageLineElement = document.createElement("div");
-        messageLineElement.className = "webkit-html-message-line";
-        messageBubbleElement.appendChild(messageLineElement);
-
         // Create the image element in the Inspector's document so we can use relative image URLs.
+        var messageLineElement = messageBubbleElement.createChild("div", "webkit-html-message-line");
         messageLineElement.appendChild(imageElement);
-        messageLineElement.appendChild(document.createTextNode(msg.messageText));
+        messageLineElement.createTextChild(msg.messageText);
 
         rowMessage.element = messageLineElement;
         rowMessage.repeatCount = 1;
         this._updateMessageRepeatCount(rowMessage);
         this._textEditor.endUpdates();
     },
 
     _updateMessageRepeatCount: function(rowMessage)
     {
         if (rowMessage.repeatCount < 2)
@@ skipping 189 matching lines @@
     onJumpToPosition: function(from, to)
     {
         this._sourceFrame.onJumpToPosition(from, to);
     }
 }
 
 importScript("GoToLineDialog.js");
 importScript("ResourceView.js");
 importScript("FontView.js");
 importScript("ImageView.js");