Remove autostart hashing code from WebCore
https://bugs.webkit.org/show_bug.cgi?id=113242

Reviewed by Tim Horton.

Remove PlugInOriginHash and all the related build entries.

* CMakeLists.txt:
* GNUmakefile.list.am:
* Target.pri:
* WebCore.gypi:
* WebCore.vcproj/WebCore.vcproj:
* WebCore.vcxproj/WebCore.vcxproj:
* WebCore.vcxproj/WebCore.vcxproj.filters:
* WebCore.xcodeproj/project.pbxproj:
* html/HTMLPlugInImageElement.cpp:
* plugins/PlugInOriginHash.cpp: Removed.
* plugins/PlugInOriginHash.h: Removed.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146833 268f45cc-cd09-0410-ab3c-d52691b4dbfc