Fix font selection for combining character sequences

Fix font selection for combining character sequences

Before this patch, SimpleFontData::canRenderCombiningCharacterSequence()
tried to determine if given SimpleFontData can render the sequence by
using SkPaint::textToGlyphs(), but it was always returning true.

After this patch, it returns true if the SimpleFontData has glyphs for
all the codepoints in the sequence.

BUG=464148
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=193236

[Kunihiko Sakamoto, 2015-03-31 10:07:49]

Patchset #1 (id:1) has been deleted

[Kunihiko Sakamoto, 2015-04-01 05:25:59]

ksakamoto@chromium.org changed reviewers:
+ eae@chromium.org

[khaledhosny, 2015-04-01 14:20:20]

On 2015/04/01 05:25:59, Kunihiko Sakamoto wrote:

I’m not familiar with Blink code, but HarfBuzz can render combining marks not
supported directly by the font if it has a precomposed form for the base + the
combining mark, so it might be better to get this information from HarfBuzz
somehow.

[eae, 2015-04-01 15:57:58]

eae@chromium.org changed reviewers:
+ behdad@chromium.org

[eae, 2015-04-01 15:57:58]

Makes sense to me, behdad how does this approach look to you?

[behdad_google, 2015-04-06 04:17:26]

On 2015/04/01 15:57:58, eae wrote:
> Makes sense to me, behdad how does this approach look to you?

Sounds good to me as well.  This is just for the simple code path, right?

[eae, 2015-04-06 15:26:53]

LGTM

[Kunihiko Sakamoto, 2015-04-07 01:09:57]

The CQ bit was checked by ksakamoto@chromium.org

[commit-bot: I haz the power, 2015-04-07 01:10:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1047123002/20001

[commit-bot: I haz the power, 2015-04-07 02:43:32]

Committed patchset #1 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=193236