SkPaint intercept API for SkTextBlob and horizontal text

Add getPosTextHIntercepts(), getTextBlobIntercepts().

Consolidate the implementation in GetTextIntercepts<> template.

BUG=chormium:581456
R=caryclark@google.com,reed@google.com
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2186663004

Review-Url: https://codereview.chromium.org/2186663004
3 files changed