Revert of Stop using SkScalerContext::getAdvance() in SkGlyphCache.

Revert of Stop using SkScalerContext::getAdvance() in SkGlyphCache. (patchset #2 id:20001 of https://codereview.chromium.org/1321243004/ )

Reason for revert:
Suspect this is the cause of regressions in crbug.com/527445.  It's triggering on Windows and Linux, where getting advances does less than getting full metrics.  It's not triggering on Mac, where this CL was a no-op.

Original issue's description:
> Stop using SkScalerContext::getAdvance() in SkGlyphCache.
> 
> We think it'll simplify things to just always get the full metrics.
> On most platforms, it's no different, and we think the platforms that
> do differ (FreeType) will be nearly just as cheap.
> 
> Removing this distinction helps us make SkGlyphCaches concurrent by
> removing a state (we-have-only-advances) from its logical state machine.
> 
> We see no significant changes running SKPs before and after this CL.
> That makes sense, of course, because the SKPs bake some of this into drawPosText.
> 
> BUG=skia:
> 
> Committed: https://skia.googlesource.com/skia/+/518a2923f11b819fa44ed5cff54155326959540f

TBR=reed@google.com,bungeman@google.com,herb@google.com,mtklein@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Committed: https://skia.googlesource.com/skia/+/8d57faf31819e714de797ba43194f199d7616c39

[mtklein, 2015-10-06 14:00:21]

Created Revert of Stop using SkScalerContext::getAdvance() in SkGlyphCache.

[commit-bot: I haz the power, 2015-10-06 14:00:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1383403003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1383403003/1

[commit-bot: I haz the power, 2015-10-06 14:00:58]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/8d57faf31819e714de797ba43194f199d7616c39