No hinting on Mac should be lower priority than subpixel rendering.

[bungeman, 2012-10-05 17:36:23]

With this change no-hinting regular anti-aliased still draws without dilation,
but preference is given to subpixel rendering so that no-hinting lcd smoothed
glyphs are still dilated (but still rendered with lcd smoothing).  In the
future, when Skia can properly render subpixel rendered glyphs from outlines,
this should be used to remove the FIXMEs remaining.

[bungeman, 2012-10-05 18:00:39]

Patch Set 2: Modified comments to make hinting levels more clear, improved cache
sharing.

[reed1, 2012-10-05 18:09:18]

lgtm

I think a block wordy comment might also be warrented somewhere:

/*
  Sometimes we can see conflicting requests. Image format [BW, AA, LCD]
  and [no-hint, yes-hint] should be orthogonal, but in reality they are not yet.
  Apple's scaler has no "switch" to enable/disable hinting.
  However, in practice, Apple's LCD output is more heavily hinted (due to
dilation, etc.) than its A8 output.

  In recognition of this, when we see a request for [AA] and [no-hint], we will
generate that AA using apple's AA output. [AA] + [yes-hint] we use Apple's LCD
output (and just smash it down to a single channel) as that output more closely
matches normal LCD in weight.

  If we see a request for [LCD] + [no-hint], we are stuck, and have to pick
which of the two to respect. We side with [LCD], and so effectively ignore the
hinting level when LCD is requested (see FilterRec).
*/

[bungeman, 2012-10-05 18:44:49]

Wordy comment added.

Committed revision 5836.