Remove more dead Chromium code
https://bugs.webkit.org/show_bug.cgi?id=114090

Reviewed by Alp Toker.

* CMakeLists.txt:
* GNUmakefile.list.am:
* Target.pri:
* WebCore.vcproj/WebCore.vcproj:
* WebCore.vcxproj/WebCore.vcxproj:
* WebCore.xcodeproj/project.pbxproj:
* platform/StatsCounter.cpp: Removed.
* platform/StatsCounter.h: Removed.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@147838 268f45cc-cd09-0410-ab3c-d52691b4dbfc