Remove ScrollView::platformInit() and ScrollView::platformDestroy()

Remove ScrollView::platformInit() and ScrollView::platformDestroy()
https://bugs.webkit.org/show_bug.cgi?id=121824

Reviewed by Darin Adler.

ScrollView::platformInit() and ScrollView::platformDestroy() are just
empty functions for all ports after removed WX port at r149186.

* PlatformEfl.cmake: Removed ScrollViewEfl.cpp from source list.
* platform/ScrollView.cpp: Removed platformInit and PlatformDestroy.
(WebCore::ScrollView::ScrollView):
(WebCore::ScrollView::~ScrollView):
* platform/ScrollView.h: Ditto.
* platform/efl/ScrollViewEfl.cpp: Removed.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@156320 268f45cc-cd09-0410-ab3c-d52691b4dbfc