Make Sk2DPathEffect thread safe.

SkPathEffects must be thread safe, but SkMatrix is only thread safe if
the type mask has already been computed. The constructor for
Sk2DPathEffect is currently making the call to 'invert' which sets the
type mask, but it is being called with the passed matrix as opposed to
the local copy.

BUG=skia:5765

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2340133004

Review-Url: https://codereview.chromium.org/2340133004
1 file changed