[turbofan] Fix JSON escapes in --trace-turbo files.

[turbofan] Fix JSON escapes in --trace-turbo files.

This makes the character escaping in the graph visualizer less generic
but correct against the JSON spec. The spec has the following definition
for valid characters within a double quoted string:

char ::
  any-Unicode-character-except-"-or-\-or-control-character
  \"
  \\
  \/
  \b
  \f
  \n
  \r
  \t
  \u four-hex-digits

R=bmeurer@chromium.org

Committed: https://crrev.com/dd144bbb039a437ce70541ae7a9abc8ccc66a946
Cr-Commit-Position: refs/heads/master@{#40364}

[Michael Starzinger, 2016-10-17 12:32:38]

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

[commit-bot: I haz the power, 2016-10-17 12:32:42]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Benedikt Meurer, 2016-10-17 12:35:33]

lgtm

[commit-bot: I haz the power, 2016-10-17 12:59:11]

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

[commit-bot: I haz the power, 2016-10-17 12:59:12]

Dry run: This issue passed the CQ dry run.

[Michael Starzinger, 2016-10-17 13:07:56]

The CQ bit was checked by mstarzinger@chromium.org

[commit-bot: I haz the power, 2016-10-17 13:08:03]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-17 13:10:18]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-10-17 13:10:44]

Description was changed from

==========
[turbofan] Fix JSON escapes in --trace-turbo files.

This makes the character escaping in the graph visualizer less generic
but correct against the JSON spec. The spec has the following definition
for valid characters within a double quoted string:

char ::
  any-Unicode-character-except-"-or-\-or-control-character
  \"
  \\
  \/
  \b
  \f
  \n
  \r
  \t
  \u four-hex-digits

R=bmeurer@chromium.org
==========

to

==========
[turbofan] Fix JSON escapes in --trace-turbo files.

This makes the character escaping in the graph visualizer less generic
but correct against the JSON spec. The spec has the following definition
for valid characters within a double quoted string:

char ::
  any-Unicode-character-except-"-or-\-or-control-character
  \"
  \\
  \/
  \b
  \f
  \n
  \r
  \t
  \u four-hex-digits

R=bmeurer@chromium.org

Committed: https://crrev.com/dd144bbb039a437ce70541ae7a9abc8ccc66a946
Cr-Commit-Position: refs/heads/master@{#40364}
==========

[commit-bot: I haz the power, 2016-10-17 13:10:45]

Patchset 1 (id:??) landed as
https://crrev.com/dd144bbb039a437ce70541ae7a9abc8ccc66a946
Cr-Commit-Position: refs/heads/master@{#40364}