Rebase GDBJIT interface solely on JITCodeEvent

Rebase GDBJIT interface solely on JITCodeEvent

R=mstarzinger@chromium.org
BUG=

Committed: https://crrev.com/652061ed7231cb722cc8246cdc7f6866110d4358
Cr-Commit-Position: refs/heads/master@{#26858}

[wingo, 2015-02-25 13:04:40]

This is a re-land of https://codereview.chromium.org/957673004/, having removed
the useless and incorrect "class JITCodeEntry;" redeclaration of the "struct
JITCodeEntry" that caused the compile error for the other one.  (I didn't catch
it as I use GCC.)

[Michael Starzinger, 2015-02-25 13:16:41]

LGTM (rubber-stamped).

[wingo, 2015-02-25 13:30:07]

The CQ bit was checked by wingo@igalia.com

[commit-bot: I haz the power, 2015-02-25 13:30:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/958623002/1

[commit-bot: I haz the power, 2015-02-25 13:43:28]

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

[commit-bot: I haz the power, 2015-02-25 13:43:29]

Try jobs failed on following builders:
  v8_linux_gcc_compile_rel on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_gcc_compile_rel/bu...)

[wingo, 2015-02-25 15:17:39]

The CQ bit was checked by wingo@igalia.com

[wingo, 2015-02-25 15:17:39]

The patchset sent to the CQ was uploaded after l-g-t-m from
mstarzinger@chromium.org
Link to the patchset: https://codereview.chromium.org/958623002/#ps20001 (title:
"Fix compilation error")

[commit-bot: I haz the power, 2015-02-25 15:18:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/958623002/20001

[commit-bot: I haz the power, 2015-02-25 15:40:46]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-02-25 15:41:15]

Patchset 2 (id:??) landed as
https://crrev.com/652061ed7231cb722cc8246cdc7f6866110d4358
Cr-Commit-Position: refs/heads/master@{#26858}