[GTK] Remove unnecessary includes in WidgetGtk.cpp
https://bugs.webkit.org/show_bug.cgi?id=115912

Reviewed by Andreas Kling.

No new tests - no new functionality.

* platform/gtk/WidgetGtk.cpp: Remove the unnecessary includes of the Chrome.h, Frame.h, FrameView.h,
Page.h and RenderObject.h headers as the included declarations are not used anywhere. ScrollView.h is
included instead as it is required and was previously included by one of the removed header inclusions.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@149895 268f45cc-cd09-0410-ab3c-d52691b4dbfc