skia: Fix text subpixel half sample default for GPU rasterization

In software, SkDraw1Glyph::Proc SkDraw1Glyph::init initializes
fHalfSampleX, fHalfSampleY to SkGlyph::kSubpixelRound.  In hardware,
however, these values were initialized to zero.

Fix, match software's implementation

BUG=471919

Review URL: https://codereview.chromium.org/1047803004
1 file changed