UNSUPPORTED is a specific error meaning an implementation-specific incompatibility. For cases where the attachments are invalid according to the spec, we should be returning INCOMPLETE_ATTACHMENT. BUG=angleproject:1231 Change-Id: I4b4332ee5661738374e93c825a53d66d7ba1fad5 Reviewed-on: https://chromium-review.googlesource.com/313995 Tryjob-Request: Jamie Madill <jmadill@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>
