Set the GTK 64-bit Debug builder to build and test only WebKit1
https://bugs.webkit.org/show_bug.cgi?id=108648

Reviewed by Philippe Normand.

* BuildSlaveSupport/build.webkit.org-config/config.json: Change the builder name, type and
build directory to note that the builder builds and tests only the WebKit1 port on the GTK platform.
* BuildSlaveSupport/build.webkit.org-config/master.cfg:
(CompileWebKit1Only): Add the new build class that builds only the WebKit1 port of the builder's platform.
(BuildAndTestWebKit1OnlyFactory): Add the new factory that uses the CompileWebKit1Only build class
for building and testing only WebKit1 on the builder's platform.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@141602 268f45cc-cd09-0410-ab3c-d52691b4dbfc