[esnext] Fix various callsites to use is_resumable, not is_generator

[esnext] Fix various callsites to use is_resumable, not is_generator

Async functions are built out of generators, but the
SharedFunctionInfo returns false for is_generator. is_resumable is
the broader query. This patch fixes many parts of V8 to refer
to is_resumable as appropriate.

One incidental change is to remove a check for generators extending
classes. This is part of a general check for constructors being the
only thing which can extend classes, so it is removed here and the
error message for the general case is made more accurate.

BUG=v8:4483
Committed: https://crrev.com/46253e743df20c67bd524cf6f4288f549cb72739
Cr-Commit-Position: refs/heads/master@{#36621}

[Dan Ehrenberg, 2016-05-20 13:09:21]

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

[commit-bot: I haz the power, 2016-05-20 13:09:33]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1996943002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1996943002/1

[Dan Ehrenberg, 2016-05-20 13:09:35]

littledan@chromium.org changed reviewers:
+ caitpotter88@gmail.com

[commit-bot: I haz the power, 2016-05-20 13:12:46]

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

[commit-bot: I haz the power, 2016-05-20 13:12:47]

Dry run: Try jobs failed on following builders:
  v8_presubmit on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_presubmit/builds/15662)

[Dan Ehrenberg, 2016-05-20 13:14:14]

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

[commit-bot: I haz the power, 2016-05-20 13:14:25]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1996943002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1996943002/20001

[commit-bot: I haz the power, 2016-05-20 13:34:18]

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

[commit-bot: I haz the power, 2016-05-20 13:34:18]

Dry run: Try jobs failed on following builders:
  v8_linux64_avx2_rel_ng on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_avx2_rel_ng/buil...)
  v8_linux64_avx2_rel_ng_triggered on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_avx2_rel_ng_trig...)

[Dan Ehrenberg, 2016-05-20 13:34:35]

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

[commit-bot: I haz the power, 2016-05-20 13:34:47]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1996943002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1996943002/40001

[Dan Ehrenberg, 2016-05-20 13:35:48]

Description was changed from

==========
[esnext] Fix various callsites to use is_resumable, not is_generator

Async functions are built out of generators, but the
SharedFunctionInfo returns false for is_generator. is_resumable is
the broader query. This patch fixes many parts of V8 to refer
to is_resumable as appropriate.

BUG=v8:4483
==========

to

==========
[esnext] Fix various callsites to use is_resumable, not is_generator

Async functions are built out of generators, but the
SharedFunctionInfo returns false for is_generator. is_resumable is
the broader query. This patch fixes many parts of V8 to refer
to is_resumable as appropriate.

One incidental change is to remove a check for generators extending
classes. This is part of a general check for constructors being the
only thing which can extend classes, so it is removed here and the
error message for the general case is made more accurate.

BUG=v8:4483
==========

[caitp (gmail), 2016-05-20 13:35:56]

https://codereview.chromium.org/1996943002/diff/1/src/debug/debug.cc
File src/debug/debug.cc (right):

https://codereview.chromium.org/1996943002/diff/1/src/debug/debug.cc#newcode1334
src/debug/debug.cc:1334: bool include_generators = !is_interpreted &&
shared->is_resumable();
I imagine this fixes what could have been broken debugger tests, had they been
written. No generator-specific tests were added in
35c28ce0a742e58346d2dea009428cacd442040d, though. Yang might be able to point
out failures corrected by this?

https://codereview.chromium.org/1996943002/diff/1/src/debug/liveedit.cc
File src/debug/liveedit.cc (right):

https://codereview.chromium.org/1996943002/diff/1/src/debug/liveedit.cc#newco...
src/debug/liveedit.cc:1675: if (shared->is_resumable()) {
Maybe a test similar to generators-debug-liveedit.js is worth having?

https://codereview.chromium.org/1996943002/diff/1/src/factory.cc
File src/factory.cc (right):

https://codereview.chromium.org/1996943002/diff/1/src/factory.cc#newcode1333
src/factory.cc:1333: if (function->shared()->is_resumable()) {
Based on how generator_object_prototype_map is created, this doesn't look
correct to me

```
  Handle<JSFunction> object_function(native_context()->object_function());
  Handle<Map> generator_object_prototype_map = Map::Create(isolate(), 0);
  Map::SetPrototype(generator_object_prototype_map, generator_object_prototype);
  native_context()->set_generator_object_prototype_map(
      *generator_object_prototype_map);
```

But I don't think this code gets reached without adding an API for creating
async functions, so I don't believe this can be verified yet

https://codereview.chromium.org/1996943002/diff/1/src/runtime/runtime-classes.cc
File src/runtime/runtime-classes.cc (right):

https://codereview.chromium.org/1996943002/diff/1/src/runtime/runtime-classes...
src/runtime/runtime-classes.cc:97:
DCHECK(!Handle<JSFunction>::cast(super_class)->shared()->is_resumable());
Is this CHECK really needed? if we have this check, why not also a bunch for
arrow functions, methods, getter/setters, etc?

https://codereview.chromium.org/1996943002/diff/1/src/runtime/runtime-classes...
src/runtime/runtime-classes.cc:113:
NewTypeError(MessageTemplate::kExtendsValueNotConstructor, super_class),
awfully similar to my CL from yesterday :p but it's cool

[commit-bot: I haz the power, 2016-05-20 13:57:38]

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

[commit-bot: I haz the power, 2016-05-20 13:57:40]

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

[Dan Ehrenberg, 2016-05-20 14:49:59]

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

[commit-bot: I haz the power, 2016-05-20 14:50:13]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1996943002/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1996943002/60001

[Dan Ehrenberg, 2016-05-20 14:57:21]

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

[commit-bot: I haz the power, 2016-05-20 14:57:33]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1996943002/80001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1996943002/80001

[Dan Ehrenberg, 2016-05-20 14:59:19]

This patch doesn't add all the debugger tests, but it fixes basic issues that
should've just been set up this way all along. What if we landed this and turned
--harmony-async-await back on for clusterfuzz while, in parallel, writing more
exhaustive debugging tests?

https://codereview.chromium.org/1996943002/diff/1/src/debug/debug.cc
File src/debug/debug.cc (right):

https://codereview.chromium.org/1996943002/diff/1/src/debug/debug.cc#newcode1334
src/debug/debug.cc:1334: bool include_generators = !is_interpreted &&
shared->is_resumable();
On 2016/05/20 at 13:35:56, caitp wrote:
> I imagine this fixes what could have been broken debugger tests, had they been
written. No generator-specific tests were added in
35c28ce0a742e58346d2dea009428cacd442040d, though. Yang might be able to point
out failures corrected by this?

Seems like this will come up if you add a breakpoint to an async function after
an await while the function is actually still awaiting the result. Let's write a
test for this (but maybe it can come in a follow-on patch?)

https://codereview.chromium.org/1996943002/diff/1/src/debug/liveedit.cc
File src/debug/liveedit.cc (right):

https://codereview.chromium.org/1996943002/diff/1/src/debug/liveedit.cc#newco...
src/debug/liveedit.cc:1675: if (shared->is_resumable()) {
On 2016/05/20 at 13:35:56, caitp wrote:
> Maybe a test similar to generators-debug-liveedit.js is worth having?

Yes

https://codereview.chromium.org/1996943002/diff/1/src/factory.cc
File src/factory.cc (right):

https://codereview.chromium.org/1996943002/diff/1/src/factory.cc#newcode1333
src/factory.cc:1333: if (function->shared()->is_resumable()) {
On 2016/05/20 at 13:35:56, caitp wrote:
> Based on how generator_object_prototype_map is created, this doesn't look
correct to me
> 
> ```
>   Handle<JSFunction> object_function(native_context()->object_function());
>   Handle<Map> generator_object_prototype_map = Map::Create(isolate(), 0);
>   Map::SetPrototype(generator_object_prototype_map,
generator_object_prototype);
>   native_context()->set_generator_object_prototype_map(
>       *generator_object_prototype_map);
> ```
> 
> But I don't think this code gets reached without adding an API for creating
async functions, so I don't believe this can be verified yet

Oh you're right, oops. The new patch asserts that we never get here for async
functions.

https://codereview.chromium.org/1996943002/diff/1/src/runtime/runtime-classes.cc
File src/runtime/runtime-classes.cc (right):

https://codereview.chromium.org/1996943002/diff/1/src/runtime/runtime-classes...
src/runtime/runtime-classes.cc:97:
DCHECK(!Handle<JSFunction>::cast(super_class)->shared()->is_resumable());
On 2016/05/20 at 13:35:56, caitp wrote:
> Is this CHECK really needed? if we have this check, why not also a bunch for
arrow functions, methods, getter/setters, etc?

Just because I'm removing old code on the basis of it being unreachable; the
DCHECK makes sure that it wasn't a mistake.

https://codereview.chromium.org/1996943002/diff/1/src/runtime/runtime-classes...
src/runtime/runtime-classes.cc:113:
NewTypeError(MessageTemplate::kExtendsValueNotConstructor, super_class),
On 2016/05/20 at 13:35:56, caitp wrote:
> awfully similar to my CL from yesterday :p but it's cool

Oops! I hadn't gotten around to reviewing it yet. Anyway worked out a test fix
in this patch; I don't think we need new tests.

[caitp (gmail), 2016-05-20 15:21:38]

On 2016/05/20 14:59:19, Dan Ehrenberg wrote:
> This patch doesn't add all the debugger tests, but it fixes basic issues that
> should've just been set up this way all along. What if we landed this and
turned
> --harmony-async-await back on for clusterfuzz while, in parallel, writing more
> exhaustive debugging tests?

I prefer if the debugger tests that are expected to be affected by these changes
are added here (particularly the liveedit thing) --- because I find it useful to
be able to find tests added for specific blame lines. But it's up to you I
guess.

About the "breakpoint after await" thing, I believe async-debug-basic.js has
that, without any kind of crashing or anything, so yeah, not sure what's missing
there.

[caitp (gmail), 2016-05-20 15:22:05]

On 2016/05/20 15:21:38, caitp wrote:
> On 2016/05/20 14:59:19, Dan Ehrenberg wrote:
> > This patch doesn't add all the debugger tests, but it fixes basic issues
that
> > should've just been set up this way all along. What if we landed this and
> turned
> > --harmony-async-await back on for clusterfuzz while, in parallel, writing
more
> > exhaustive debugging tests?
> 
> I prefer if the debugger tests that are expected to be affected by these
changes
> are added here (particularly the liveedit thing) --- because I find it useful
to
> be able to find tests added for specific blame lines. But it's up to you I
> guess.
> 
> About the "breakpoint after await" thing, I believe async-debug-basic.js has
> that, without any kind of crashing or anything, so yeah, not sure what's
missing
> there.

Otherwise lgtm, fwiw

[commit-bot: I haz the power, 2016-05-20 15:29:54]

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

[commit-bot: I haz the power, 2016-05-20 15:29:55]

Dry run: Try jobs failed on following builders:
  v8_linux64_avx2_rel_ng on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_avx2_rel_ng/buil...)
  v8_linux64_avx2_rel_ng_triggered on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_avx2_rel_ng_trig...)

[Dan Ehrenberg, 2016-05-27 14:31:01]

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

[commit-bot: I haz the power, 2016-05-27 14:31:11]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1996943002/100001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1996943002/100001

[commit-bot: I haz the power, 2016-05-27 14:47:41]

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

[commit-bot: I haz the power, 2016-05-27 14:47:42]

Dry run: Try jobs failed on following builders:
  v8_linux64_avx2_rel_ng on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_avx2_rel_ng/buil...)
  v8_linux64_avx2_rel_ng_triggered on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_avx2_rel_ng_trig...)
  v8_win_nosnap_shared_rel_ng on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_win_nosnap_shared_rel_ng...)
  v8_win_nosnap_shared_rel_ng_triggered on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_win_nosnap_shared_rel_ng...)

[Dan Ehrenberg, 2016-05-27 15:50:21]

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

[commit-bot: I haz the power, 2016-05-27 15:50:32]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1996943002/120001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1996943002/120001

[commit-bot: I haz the power, 2016-05-27 16:09:51]

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

[commit-bot: I haz the power, 2016-05-27 16:09:52]

Dry run: Try jobs failed on following builders:
  v8_linux64_rel_ng on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_rel_ng/builds/6418)
  v8_linux64_rel_ng_triggered on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_rel_ng_triggered...)

[Dan Ehrenberg, 2016-05-27 17:04:03]

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

[commit-bot: I haz the power, 2016-05-27 17:04:09]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1996943002/140001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1996943002/140001

[commit-bot: I haz the power, 2016-05-27 17:22:39]

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

[commit-bot: I haz the power, 2016-05-27 17:22:40]

Dry run: Try jobs failed on following builders:
  v8_linux64_rel_ng on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_rel_ng/builds/6420)
  v8_linux64_rel_ng_triggered on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_rel_ng_triggered...)

[Dan Ehrenberg, 2016-05-27 17:35:57]

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

[commit-bot: I haz the power, 2016-05-27 17:36:09]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1996943002/140001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1996943002/140001

[commit-bot: I haz the power, 2016-05-27 17:40:59]

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

[commit-bot: I haz the power, 2016-05-27 17:41:01]

Dry run: Try jobs failed on following builders:
  v8_linux64_avx2_rel_ng on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_avx2_rel_ng/buil...)
  v8_linux64_avx2_rel_ng_triggered on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_avx2_rel_ng_trig...)

[Dan Ehrenberg, 2016-05-27 18:08:24]

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

[commit-bot: I haz the power, 2016-05-27 18:08:27]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1996943002/160001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1996943002/160001

[commit-bot: I haz the power, 2016-05-27 18:36:41]

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

[commit-bot: I haz the power, 2016-05-27 18:36:43]

Dry run: This issue passed the CQ dry run.

[Dan Ehrenberg, 2016-05-27 19:13:35]

littledan@chromium.org changed reviewers:
+ adamk@chromium.org

[adamk, 2016-05-27 20:42:29]

adamk@chromium.org changed reviewers:
+ yangguo@chromium.org

[adamk, 2016-05-27 20:42:29]

+yang

This seems like the right way for the code to look, but I do think that this fix
ought to have regression tests land along with it.

[Yang, 2016-05-30 12:32:46]

LGTM.

I assume we are going to have some tests that have async functions on the stack
when we start stepping and/or set break points? (see
test/mjsunit/ignition/debug-break-on-stack).

https://codereview.chromium.org/1996943002/diff/160001/src/debug/debug.cc
File src/debug/debug.cc (right):

https://codereview.chromium.org/1996943002/diff/160001/src/debug/debug.cc#new...
src/debug/debug.cc:1332: bool include_generators = !is_interpreted &&
shared->is_resumable();
how about we rename "include_generators" to "find_resumable"?

[Dan Ehrenberg, 2016-05-31 08:53:37]

Working on tests.

https://codereview.chromium.org/1996943002/diff/160001/src/debug/debug.cc
File src/debug/debug.cc (right):

https://codereview.chromium.org/1996943002/diff/160001/src/debug/debug.cc#new...
src/debug/debug.cc:1332: bool include_generators = !is_interpreted &&
shared->is_resumable();
On 2016/05/30 at 12:32:46, Yang wrote:
> how about we rename "include_generators" to "find_resumable"?

Good idea, done.

[Dan Ehrenberg, 2016-05-31 16:08:25]

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

[commit-bot: I haz the power, 2016-05-31 16:08:36]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1996943002/240001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1996943002/240001

[commit-bot: I haz the power, 2016-05-31 16:12:25]

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

[commit-bot: I haz the power, 2016-05-31 16:12:27]

Dry run: Try jobs failed on following builders:
  v8_presubmit on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_presubmit/builds/16234)

[Dan Ehrenberg, 2016-05-31 16:20:08]

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

[commit-bot: I haz the power, 2016-05-31 16:20:16]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1996943002/260001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1996943002/260001

[commit-bot: I haz the power, 2016-05-31 16:25:06]

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

[commit-bot: I haz the power, 2016-05-31 16:25:07]

Dry run: Try jobs failed on following builders:
  v8_presubmit on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_presubmit/builds/16237)

[Dan Ehrenberg, 2016-05-31 16:28:44]

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

[commit-bot: I haz the power, 2016-05-31 16:28:56]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1996943002/280001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1996943002/280001

[Dan Ehrenberg, 2016-05-31 16:51:08]

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

[commit-bot: I haz the power, 2016-05-31 16:51:10]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1996943002/300001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1996943002/300001

[Dan Ehrenberg, 2016-05-31 17:10:15]

The CQ bit was unchecked by littledan@chromium.org

[Dan Ehrenberg, 2016-05-31 17:10:20]

The CQ bit was checked by littledan@chromium.org

[Dan Ehrenberg, 2016-05-31 17:10:20]

The patchset sent to the CQ was uploaded after l-g-t-m from
caitpotter88@gmail.com, yangguo@chromium.org
Link to the patchset: https://codereview.chromium.org/1996943002/#ps300001
(title: "don't pass unneeded zero")

[commit-bot: I haz the power, 2016-05-31 17:10:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1996943002/300001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1996943002/300001

[Dan Ehrenberg, 2016-05-31 17:13:02]

On 2016/05/31 at 16:51:10, commit-bot wrote:
> Dry run: CQ is trying da patch. Follow status at
>  https://chromium-cq-status.appspot.com/patch-status/1996943002/300001
> View timeline at
>  https://chromium-cq-status.appspot.com/patch-timeline/1996943002/300001

Committing with some tests which caitp reviewed. No liveedit tests yet; there
just aren't any tests for the failure path at all, and there also aren't any
tests (besides the ones added in this patch) that tests debugging generators.
Caitlin and I will work on these tests and more, based on Yang's suggestion, but
would like to have this in so that we can turn back on es-staging for
async/await and get more Clusterfuzz feedback.

[commit-bot: I haz the power, 2016-05-31 17:14:07]

Committed patchset #16 (id:300001)

[commit-bot: I haz the power, 2016-05-31 17:15:30]

Description was changed from

==========
[esnext] Fix various callsites to use is_resumable, not is_generator

Async functions are built out of generators, but the
SharedFunctionInfo returns false for is_generator. is_resumable is
the broader query. This patch fixes many parts of V8 to refer
to is_resumable as appropriate.

One incidental change is to remove a check for generators extending
classes. This is part of a general check for constructors being the
only thing which can extend classes, so it is removed here and the
error message for the general case is made more accurate.

BUG=v8:4483
==========

to

==========
[esnext] Fix various callsites to use is_resumable, not is_generator

Async functions are built out of generators, but the
SharedFunctionInfo returns false for is_generator. is_resumable is
the broader query. This patch fixes many parts of V8 to refer
to is_resumable as appropriate.

One incidental change is to remove a check for generators extending
classes. This is part of a general check for constructors being the
only thing which can extend classes, so it is removed here and the
error message for the general case is made more accurate.

BUG=v8:4483

Committed: https://crrev.com/46253e743df20c67bd524cf6f4288f549cb72739
Cr-Commit-Position: refs/heads/master@{#36621}
==========

[commit-bot: I haz the power, 2016-05-31 17:15:32]

Patchset 16 (id:??) landed as
https://crrev.com/46253e743df20c67bd524cf6f4288f549cb72739
Cr-Commit-Position: refs/heads/master@{#36621}