Simplify V8 wrapper generation for Event objects

Simply V8 wrapper generation for Event objects

When trying to determine what kind of wrapper to produce, we'd iterate
over core event types (exiting early) then try iterating over module
event types. If the latter yielded an empty handle we'd wrap the
object as just a V8Event, which is bogus. This could happen in a
worker if the object was indeed a module event type, but the worker
had been asynchronously stopped and v8 was politely failing to produce
a wrapper.

Remove the fallback case, and instead assert if we make it as far as
module event type iteration and no match is found.

BUG=395411
R=abarth,tasak

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=179340

[jsbell, 2014-07-31 16:40:22]

abarth@, tasak@ - Please take a look?

[haraken, 2014-07-31 16:51:01]

LGTM

> but the worker had been asynchronously stopped and v8 was politely failing to
produce a wrapper.

However, this is a separate issue. When the main thread sends a
TerminateExecution() to a worker, any V8 API running in the worker at that point
can return an empty handle. Currently we don't have code to handle the
situation, so whatever can happen.

I've asked a plan about how to handle the situation here
(https://code.google.com/p/chromium/issues/detail?id=301515#c15), but no rely
yet.

https://codereview.chromium.org/424813007/diff/1/Source/bindings/modules/v8/M...
File Source/bindings/modules/v8/ModuleBindingsInitializer.cpp (right):

https://codereview.chromium.org/424813007/diff/1/Source/bindings/modules/v8/M...
Source/bindings/modules/v8/ModuleBindingsInitializer.cpp:29:
ASSERT_NOT_REACHED();

Would you add a comment and mention what hitting the ASSERT means?

[jsbell, 2014-07-31 17:12:33]

The CQ bit was checked by jsbell@chromium.org

[commit-bot: I haz the power, 2014-07-31 17:12:49]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jsbell@chromium.org/424813007/20001

[jsbell, 2014-07-31 17:14:01]

On 2014/07/31 16:51:01, haraken wrote:
> LGTM
> 
> > but the worker had been asynchronously stopped and v8 was politely failing
to
> produce a wrapper.
> 
> However, this is a separate issue. When the main thread sends a
> TerminateExecution() to a worker, any V8 API running in the worker at that
point
> can return an empty handle. Currently we don't have code to handle the
> situation, so whatever can happen.

Yep. Is that new, though?

> I've asked a plan about how to handle the situation here
> (https://code.google.com/p/chromium/issues/detail?id=301515#c15), but no rely
> yet.

I'll watch, now that my interest is piqued.

>
https://codereview.chromium.org/424813007/diff/1/Source/bindings/modules/v8/M...
> File Source/bindings/modules/v8/ModuleBindingsInitializer.cpp (right):
> 
>
https://codereview.chromium.org/424813007/diff/1/Source/bindings/modules/v8/M...
> Source/bindings/modules/v8/ModuleBindingsInitializer.cpp:29:
> ASSERT_NOT_REACHED();
> 
> Would you add a comment and mention what hitting the ASSERT means?

Done.

[jsbell, 2014-07-31 17:14:25]

The CQ bit was unchecked by jsbell@chromium.org

[jsbell, 2014-07-31 17:15:42]

The CQ bit was checked by jsbell@chromium.org

[commit-bot: I haz the power, 2014-07-31 17:17:07]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jsbell@chromium.org/424813007/40001

[haraken, 2014-07-31 17:18:12]

> > > but the worker had been asynchronously stopped and v8 was politely failing
> to
> > produce a wrapper.
> > 
> > However, this is a separate issue. When the main thread sends a
> > TerminateExecution() to a worker, any V8 API running in the worker at that
> point
> > can return an empty handle. Currently we don't have code to handle the
> > situation, so whatever can happen.
> 
> Yep. Is that new, though?

I think this is a longstanding issue. My guess is that some recent change just
happened to expose the issue in event wrapping code...

I think jochen would know better.

[commit-bot: I haz the power, 2014-07-31 18:26:06]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  linux_blink_dbg on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_blink_dbg/builds/1...)
  mac_blink_compile_dbg on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/mac_blink_compile_dbg/bu...)
  linux_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/linux_gpu_trigger...)
  mac_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu_triggered...)

[commit-bot: I haz the power, 2014-07-31 19:31:25]

Change committed as 179340