Unreviewed. Fix make distcheck.

Source/WebCore:

* GNUmakefile.list.am: Add missing files to compilation.

Source/WebKit/gtk:

* GNUmakefile.am: Add -DBUILDING_WEBKIT flags to introspection
scanner.

Source/WebKit2:

* GNUmakefile.am: Add -DBUILDING_WEBKIT flags to introspection
scanner.
* GNUmakefile.list.am: Add missing header to compilation and
remove one that no longer exists.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@143591 268f45cc-cd09-0410-ab3c-d52691b4dbfc