Remove unused text encoding quirks.

Remove unused text encoding quirks.

1) Remove more Backslash-as-JPY hacks (some encodings interpret backslash as yen
sign).

The code was added in https://bugs.webkit.org/show_bug.cgi?id=49714 (r73566).

The test used to be
editing/selection/find-yensign-and-backslash-with-japanese-fonts-expected.html

The feature was removed by https://codereview.chromium.org/27030014 (r159589),
but the removal was incomplete. This CL removes the leftover code and test
expectation files (the corresponding tests were removed by r159589).

2) Remove isJapaneseEncoding from TextEncodingRegistry.cpp; it was dead
code. There used to be bool TextEncoding::isJapanese() (see r16245) which was
used by WebCore/loader/Decoder.cpp... but TextEncoding::isJapanese no longer
exists, and isJapaneseEncoding appears not to be used any more.

BUG=

[marja, 2014-06-13 09:30:14]

jshin, eseidel, ptal.

[abarth-chromium, 2014-06-13 17:34:17]

That's amazing!  LGTM assuming this change is fine with jshin.

[jungshik at Google, 2014-06-17 17:10:10]

On 2014/06/13 17:34:17, abarth wrote:
> That's amazing!  LGTM assuming this change is fine with jshin.

Yeah. a couple of weeks ago, I noticed that I had overlooked removing these
additional code in 
https://codereview.chromium.org/27030014.  I meant to get rid of them, too. 

Thank you for doing this.

[jungshik at Google, 2014-06-17 17:11:21]

On 2014/06/17 17:10:10, Jungshik Shin wrote:
> On 2014/06/13 17:34:17, abarth wrote:
> > That's amazing!  LGTM assuming this change is fine with jshin.
> 
> Yeah. a couple of weeks ago, I noticed that I had overlooked removing these
> additional code in 
> https://codereview.chromium.org/27030014.  I meant to get rid of them, too. 
> 
> Thank you for doing this.

LGTM

[marja, 2014-06-18 06:58:19]

The CQ bit was checked by marja@chromium.org

[commit-bot: I haz the power, 2014-06-18 06:59:16]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/marja@chromium.org/335803002/1

[commit-bot: I haz the power, 2014-06-18 10:07:24]

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

[commit-bot: I haz the power, 2014-06-18 10:07:25]

Try jobs failed on following builders:
  win_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/12460)

[marja, 2014-06-18 13:05:28]

I committed this manually but git cl failed to post an update. Closing.