Move SkDOM and ilk from include/xml to src/xml.
I have looked for uses of SkDOM in the depot using cs/ and have found none,
but this is not perfect. So, if this breaks external builds, revert it.
TBR=reed@google.com
Change-Id: I162a1977f0649b049c0f93f016701784d025996d
Reviewed-on: https://skia-review.googlesource.com/8447
Reviewed-by: Herb Derby <herb@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Herb Derby <herb@google.com>
5a8fe978c3