Don't require templates for application of -webkit-border-image.

Trivial cleanup; the application of -webkit-border-image doesn't need to
be generated. The macro previously had two callers, but the other caller
was removed in crrev.com/50233002.

BUG=

Review URL: https://codereview.chromium.org/98013002

git-svn-id: svn://svn.chromium.org/blink/trunk@162942 bbb929c8-8fbe-4397-9dbb-9b2b20218538