Removed declaration of getAttachedShaders() without implementation. Found while working on BUG=angle:751 BUG=angle:751 Change-Id: I8a5c5383f88ecb379395d1a23e36148145ebe34d Reviewed-on: https://chromium-review.googlesource.com/224090 Tested-by: Tibor Ouden, den <tibordenouden@gmail.com> Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>