Unreviewed, fixing the GTK WK2 debug build after r155911.

* UIProcess/API/gtk/WebKitFaviconDatabase.cpp: Add missing using
namespace WebCore.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@155930 268f45cc-cd09-0410-ab3c-d52691b4dbfc
Move <style scoped> code behind ENABLE(STYLE_SCOPED)
<https://webkit.org/b/121018>

Reviewed by Darin Adler.

Move all the code for <style scoped> behind ENABLE(STYLE_SCOPED) guards.
It's not nice to clutter common codepaths with code that always executes
even though the feature is disabled at compile-time.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@155931 268f45cc-cd09-0410-ab3c-d52691b4dbfc