Add PS 'all' weight name to scanFont.

Add PS 'all' weight name to scanFont.

Multiple Master fonts often list their weight as 'all'. However, they
usually default to normal weight. State explicitly that we know about
this weight string.

Committed: https://skia.googlesource.com/skia/+/d803cdad725b6db07b6df0ae7f390f5dbef46475

[bungeman-skia, 2015-04-16 21:04:50]

The CQ bit was checked by bungeman@google.com to run a CQ dry run

[commit-bot: I haz the power, 2015-04-16 21:05:06]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1092793002/20001

[bungeman-skia, 2015-04-16 21:07:54]

bungeman@google.com changed reviewers:
+ mtklein@google.com

[bungeman-skia, 2015-04-16 21:07:55]

This doesn't change any actual current behavior, since the weight will default
to 'normal'. However, this does allow us to explicitly state that we know about
this weight string and what it implies. This makes it easier to state in the
future when we don't know what the 'default' weight of the font is.

[commit-bot: I haz the power, 2015-04-16 21:11:50]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-04-16 21:11:51]

Dry run: This issue passed the CQ dry run.

[mtklein, 2015-04-16 21:19:56]

lgtm

[bungeman-skia, 2015-04-16 21:22:16]

The CQ bit was checked by bungeman@google.com

[commit-bot: I haz the power, 2015-04-16 21:22:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1092793002/20001

[commit-bot: I haz the power, 2015-04-16 21:22:49]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/d803cdad725b6db07b6df0ae7f390f5dbef46475