https://bugs.webkit.org/show_bug.cgi?id=18500

        Reviewed by Adam Roben.

        * page/inspector/ResourcesPanel.js:
        (WebInspector.ResourceSidebarTreeElement): Call createIconElement before
        calling the superclass.
        (WebInspector.ResourceSidebarTreeElement.prototype.createIconElement):
        Create an iconElement, if the category is images then make a div that
        contains a preview image. Otherwise just make an img element. If there
        was a previous iconElement, then replace it.
        (WebInspector.ResourceSidebarTreeElement.prototype.refresh): Call
        createIconElement if the category changed.
        * page/inspector/SidebarTreeElement.js:
        (WebInspector.SidebarTreeElement): Create an iconElement if one hasn't
        been made already by a subclass.
        (WebInspector.SidebarTreeElement.prototype.onattach): Append the iconElement
        instead of creating one each time.
        * page/inspector/inspector.css: New and updated style rules.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@34272 268f45cc-cd09-0410-ab3c-d52691b4dbfc