Do not use js builtins object to determine whether a function is a builtin.

Do not use js builtins object to determine whether a function is a builtin.

We can use the script type to determine that instead. Script of type
TYPE_NATIVE are considered builtins, TYPE_NORMAL are not. The only exception
to this rule is the empty function, for which the script is TYPE_NATIVE
(observable by the debugger), but should be stringified to "function () {}"
instead of "function () { [native code] }". For this, I introduce a
hide_source flag on the script object.

We also use IsBuiltin and IsSubjectToDebugging interchangeably. For debugger,
we now use the latter, hiding the detail that only non-builtins are debuggable.

R=mstarzinger@chromium.org

Committed: https://crrev.com/371ad73a50f2c55286f59b34ca63920b44ca835f
Cr-Commit-Position: refs/heads/master@{#30285}

[Yang, 2015-08-20 13:28:59]

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

[commit-bot: I haz the power, 2015-08-20 13:29:14]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1292283004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1292283004/1

[commit-bot: I haz the power, 2015-08-20 13:44:37]

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

[commit-bot: I haz the power, 2015-08-20 13:44:38]

Dry run: Try jobs failed on following builders:
  v8_linux64_rel on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_rel/builds/8840)

[Yang, 2015-08-21 08:17:46]

yangguo@chromium.org changed reviewers:
+ mstarzinger@chromium.org
- mvstanton@chromium.org

[Yang, 2015-08-21 08:18:06]

Michael, please take a look. Thanks.

[Yang, 2015-08-21 08:18:15]

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

[commit-bot: I haz the power, 2015-08-21 08:18:26]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1292283004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1292283004/20001

[Michael Starzinger, 2015-08-21 08:30:18]

LGTM. As discussed offline: This makes the empty function now be not inlineable
and not show up on stacktraces. Both shouldn't be a real problem.

[commit-bot: I haz the power, 2015-08-21 08:42:24]

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

[commit-bot: I haz the power, 2015-08-21 08:42:25]

Dry run: This issue passed the CQ dry run.

[Yang, 2015-08-21 08:51:08]

The CQ bit was checked by yangguo@chromium.org

[Yang, 2015-08-21 08:51:08]

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/1292283004/#ps40001
(title: "remove redundant check")

[commit-bot: I haz the power, 2015-08-21 08:51:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1292283004/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1292283004/40001

[commit-bot: I haz the power, 2015-08-21 09:13:01]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-08-21 09:13:17]

Patchset 3 (id:??) landed as
https://crrev.com/371ad73a50f2c55286f59b34ca63920b44ca835f
Cr-Commit-Position: refs/heads/master@{#30285}