text-justify fix for Chinese and Japanese

text-justify has been broken for Chinese and Japanese. This patch fixes this
to the same behavior of WebKit.

There are 3 code path to justify; LChar+SimpleShaper, UChar+SimplerShaper,
and UChar+HarfbuzzShaper. This patch fixes UChar and SimpleShaper code
path. Chinese and Japanese justification always occur at UChar (not LChar),
and SimpleShaper is used most of the time for these scripts. I'll work on
complex path later in another patch.

Tests imported from WebKit were rebaselined to incorrect results at some
point. I rebaselined all such tests by looking at them and by comparing the
results with WebKit. Also one ref test was added.

Note that Chinese/Japanese justification had been disabled under the switch
|canExpandAroundIdeographsInComplexText| for Blink except on Mac, and
then it was removed because it's off in
https://codereview.chromium.org/618383003.

What this patch means in that context is to fix SimpleShaper to support the
switch and turn it back always, as long as text-justify: auto, which is the same
as WebKit behavior.

BUG=248894, 368108
TEST=fast/text/justify-ideograph.html

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=187112

[kojii, 2014-12-12 14:53:01]

Patchset #1 (id:1) has been deleted

[kojii, 2014-12-14 04:49:48]

kojii@chromium.org changed reviewers:
+ eae@chromium.org, leviw@chromium.org

[kojii, 2014-12-14 04:52:11]

leviw@, PTAL!

The code removed in
https://codereview.chromium.org/618383003
were disabled for a long time because it was not working correctly,
but it actually should be fixed and enabled rather than removed.

[leviw_travelin_and_unemployed, 2014-12-15 02:53:12]

Thanks for the detailed explanation. LGTM.

[kojii, 2014-12-15 03:57:34]

The CQ bit was checked by kojii@chromium.org

[commit-bot: I haz the power, 2014-12-15 03:57:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/766053004/80001

[commit-bot: I haz the power, 2014-12-15 04:00:05]

Committed patchset #4 (id:80001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=187112