Skip runs without printable glyphs in HarfBuzzShaper
Skip runs without printable glyphs in HarfBuzzShaper

Change HarfBuzzShaper to skip a run unless it contains one or more glyph
when shaping and filling the buffer as fillGlyphBuffer assumes that each
run has at least one printable glyph. This also allows us to remove many
of the hasGlyphToCharacterIndexes checks and replace them with numGlyphs
> 0 checks which make a lot more sense.

R=fmalita@chromium.org
BUG=444888

Review URL: https://codereview.chromium.org/826253003

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@187763 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs