Remove obsolete forward declaration from InspectorFrontendHost.h
https://bugs.webkit.org/show_bug.cgi?id=117017

Patch by Seokju Kwon <seokju.kwon@gmail.com> on 2013-05-30
Reviewed by Joseph Pecoraro.

Remove obsolete forward declaration and fix style issue as well.

No change in behavior, no new tests.

* inspector/InspectorFrontendHost.h:
(WebCore):
(InspectorFrontendHost):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@150953 268f45cc-cd09-0410-ab3c-d52691b4dbfc