Clear recorded slots when making a string external.

Clear recorded slots when making a string external.

Slots in ConsString/SlicedString can point to an evacutaion candidate.
The MakeExternal function makes in-place conversion to external string.
After the conversion we can have a recorded slot containing an external
pointer. As long as the external pointer is aligned, this is not a
problem. We clear the recorded slots to fix verify-heap checks.

BUG=chromium:631969
LOG=NO

[ulan, 2016-08-01 18:13:02]

ulan@chromium.org changed reviewers:
+ jkummerow@chromium.org

[ulan, 2016-08-01 18:13:02]

ptal

[Jakob Kummerow, 2016-08-02 11:34:09]

LGTM, thanks for fixing this!

https://codereview.chromium.org/2199863002/diff/20001/test/cctest/heap/test-h...
File test/cctest/heap/test-heap.cc (right):

https://codereview.chromium.org/2199863002/diff/20001/test/cctest/heap/test-h...
test/cctest/heap/test-heap.cc:6815: // Allocate two string in a fresh page and
mark the page as evacuation
nit: s/string/strings/

[ulan, 2016-08-02 15:00:24]

https://codereview.chromium.org/2199863002/diff/20001/test/cctest/heap/test-h...
File test/cctest/heap/test-heap.cc (right):

https://codereview.chromium.org/2199863002/diff/20001/test/cctest/heap/test-h...
test/cctest/heap/test-heap.cc:6815: // Allocate two string in a fresh page and
mark the page as evacuation
On 2016/08/02 11:34:08, Jakob wrote:
> nit: s/string/strings/

Done.

[ulan, 2016-08-02 15:00:28]

The CQ bit was checked by ulan@chromium.org

[ulan, 2016-08-02 15:00:29]

The patchset sent to the CQ was uploaded after l-g-t-m from
jkummerow@chromium.org
Link to the patchset: https://codereview.chromium.org/2199863002/#ps40001
(title: "fix typo")

[commit-bot: I haz the power, 2016-08-02 15:00:31]

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, 2016-08-02 15:19:15]

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

[commit-bot: I haz the power, 2016-08-02 15:19:17]

Try jobs failed on following builders:
  v8_linux_dbg_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_dbg_ng/builds/10145)
  v8_linux_dbg_ng_triggered on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_dbg_ng_triggered/b...)

[ulan, 2016-08-05 10:37:42]

The CQ bit was checked by ulan@chromium.org

[ulan, 2016-08-05 10:37:42]

The patchset sent to the CQ was uploaded after l-g-t-m from
jkummerow@chromium.org
Link to the patchset: https://codereview.chromium.org/2199863002/#ps60001
(title: "clear only if has pointers")

[commit-bot: I haz the power, 2016-08-05 10:37:55]

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, 2016-08-05 10:57:01]

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

[commit-bot: I haz the power, 2016-08-05 10:57:02]

Try jobs failed on following builders:
  v8_linux64_asan_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_asan_rel_ng/buil...)
  v8_linux64_asan_rel_ng_triggered on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_asan_rel_ng_trig...)