Web Inspector: Fixed DOM Breakpoint pane styles.
https://bugs.webkit.org/show_bug.cgi?id=113688

Patch by Vladislav Kaznacheev <kaznacheev@chromium.org> on 2013-04-01
Reviewed by Pavel Feldman.

The required stylesheet (breakpointsList.css) was not loaded because of
the peculiar way DOMBreakpointsSidebarPane is included in two panels
(Sources and Elements) via a proxy pane. Since DOMBreakpointsSidebarPane
was never shown directly the registerRequiredCSS call in its base class
NativeBreakpointsSidebarPane constructor had no effect.
Addin a registerRequiredCSS call to the proxy pane constructor fixes the
problem.

* inspector/front-end/DOMBreakpointsSidebarPane.js:
(WebInspector.DOMBreakpointsSidebarPane.Proxy):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@147314 268f45cc-cd09-0410-ab3c-d52691b4dbfc