Rename valgrind_layout to valgrind_webkit
Rename valgrind_layout to valgrind_webkit

This will allow for more uniform buildbot factories

BUG=none
TEST=none


Review URL: http://codereview.chromium.org/6685121

git-svn-id: http://src.chromium.org/svn/trunk/src@78927 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: d3d14de4ad6c0a60a2daa1119a691020ac777ae0
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser