Interpret linearMetrics flag to imply no-hinting.

When drawing text and the linearMetrics flag is set, interpret it as a
'linear' flag which implies no-hinting. This will keep existing behavior
and match how the flag is currently documented when Skia changes the
behavior to be seperable from hinting.

Test: Strict improvement, broken tests will be fixed before landing.
Change-Id: Ie76f84e4fd23f4086a2f955b37d3be140452e77f