[GTK] Merge RenderThemeGtk3.cpp into RenderThemeGtk.cpp and ScrollbarThemeGtk3.cpp intoScrollbarThemeGtk.cpp
https://bugs.webkit.org/show_bug.cgi?id=136336

Reviewed by Philippe Normand.

There's no reason to have two files now that there's no GTK+2
support. Also fix coding style issues and compile warnings.

* PlatformGTK.cmake:
* platform/gtk/RenderThemeGtk.cpp:
* platform/gtk/RenderThemeGtk.h:
* platform/gtk/RenderThemeGtk3.cpp: Removed.
* platform/gtk/ScrollbarThemeGtk.cpp:
* platform/gtk/ScrollbarThemeGtk3.cpp: Removed.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@173109 268f45cc-cd09-0410-ab3c-d52691b4dbfc
[GTK] ScrollbarThemeGtk should not depend on RenderThemeGtk
https://bugs.webkit.org/show_bug.cgi?id=136338

Reviewed by Philippe Normand.

Remove the dependency by creating the GtkStyleContext for the
scrollbars in ScrollbarThemeGtk.

* platform/gtk/RenderThemeGtk.cpp:
(WebCore::gtkStyleChangedCallback): Call ScrollbarThemeGtk::themeChanged().
(WebCore::getStyleContext): Remove the scrollbar style context support.
* platform/gtk/RenderThemeGtk.h: Remove gtkScrollbarStyle().
* platform/gtk/ScrollbarThemeGtk.cpp:
(WebCore::ScrollbarStyleContext::ScrollbarStyleContext): Helper
class to create the global GtkStyleContext for scrollbars.
(WebCore::ScrollbarStyleContext::~ScrollbarStyleContext):
(WebCore::ScrollbarStyleContext::context):
(WebCore::gtkScrollbarStyleContext):
(WebCore::ScrollbarThemeGtk::ScrollbarThemeGtk): Remove m_context initialization.
(WebCore::ScrollbarThemeGtk::themeChanged): Invalidate the
GtkStylecontext and call updateThemeProperties().
(WebCore::ScrollbarThemeGtk::updateThemeProperties): Use the
global style context.
(WebCore::ScrollbarThemeGtk::paintTrackBackground): Ditto.
(WebCore::ScrollbarThemeGtk::paintScrollbarBackground): Ditto.
(WebCore::ScrollbarThemeGtk::paintThumb): Ditto.
(WebCore::ScrollbarThemeGtk::paintButton): Ditto.
* platform/gtk/ScrollbarThemeGtk.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@173110 268f45cc-cd09-0410-ab3c-d52691b4dbfc