Remove SkDOM::build(const char doc[], size_t len)

This flavor is unused, and we have the more general SkStream API.

R=stephana@google.com,reed@google.com
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2154733003

Review-Url: https://codereview.chromium.org/2154733003
3 files changed