[TextBlob] Fall back to TightRunBounds when the font bounds are empty

[TextBlob] Fall back to TightRunBounds when the font bounds are empty

Empty font bounds are likely an indication of a font bug.  As a best
effort, we can use TightRunBounds in this easily detectable case.

BUG=507022
R=reed@google.com,bungeman@google.com

Committed: https://skia.googlesource.com/skia/+/d6b99cc6b84b3ec864221cbe9945d203bd9eb072

[f(malita), 2015-08-10 16:06:23]

The CQ bit was checked by fmalita@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-10 16:06:27]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1284693002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1284693002/1

[reed1, 2015-08-10 16:08:45]

Ugh, I hate that the client needed to to this.. but it makes sense to me.

lgtm

[commit-bot: I haz the power, 2015-08-10 16:21:38]

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

[commit-bot: I haz the power, 2015-08-10 16:21:39]

Dry run: This issue passed the CQ dry run.

[f(malita), 2015-08-10 16:23:53]

The CQ bit was checked by fmalita@chromium.org

[commit-bot: I haz the power, 2015-08-10 16:23:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1284693002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1284693002/1

[commit-bot: I haz the power, 2015-08-10 16:24:36]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/d6b99cc6b84b3ec864221cbe9945d203bd9eb072

[egdaniel, 2015-08-10 18:02:27]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1283853002/ by egdaniel@google.com.

The reason for reverting is: Breaking DEPS roll on Assert in
SkTextBlobBuilder::TightRunBounds..

[fmalita_google_do_not_use, 2015-08-10 18:05:55]

On 2015/08/10 18:02:27, egdaniel wrote:
> A revert of this CL (patchset #1 id:1) has been created in
> https://codereview.chromium.org/1283853002/ by mailto:egdaniel@google.com.
> 
> The reason for reverting is: Breaking DEPS roll on Assert in
> SkTextBlobBuilder::TightRunBounds..

Yup, I believe the assert is correct: TightRunBounds assumes default glyph
advances.  We'll need to do some extra work to support the other positioning
modes.