Support stepping into generator function.

Support stepping into generator function.

R=aandrey@chromium.org, wingo@igalia.com
BUG=v8:3572
LOG=Y

Committed: https://code.google.com/p/v8/source/detail?r=24000

[aandrey, 2014-09-17 11:29:34]

Needs a test, otherwise looking good.

[wingo, 2014-09-17 11:30:03]

lgtm; a test would be nice, though I know how irritating debugger tests can be

https://codereview.chromium.org/544953005/diff/1/src/generator.js
File src/generator.js (right):

https://codereview.chromium.org/544953005/diff/1/src/generator.js#newcode23
src/generator.js:23: if (DEBUG_IS_ACTIVE) %DebugPrepareStepInIfStepping(this);
Is this needed at almost every use of %_CallFunction?  Looks to me like there
are more of these sites needing %DebugPrepareStepInIfStepping in the runtime .js
files that are unrelated to generators.

[Yang, 2014-09-17 11:33:26]

On 2014/09/17 11:29:34, aandrey wrote:
> Needs a test, otherwise looking good.

I had a test. Just forgot to add it to the commit.

[Yang, 2014-09-17 11:35:30]

On 2014/09/17 11:30:03, wingo wrote:
> lgtm; a test would be nice, though I know how irritating debugger tests can be
> 
> https://codereview.chromium.org/544953005/diff/1/src/generator.js
> File src/generator.js (right):
> 
> https://codereview.chromium.org/544953005/diff/1/src/generator.js#newcode23
> src/generator.js:23: if (DEBUG_IS_ACTIVE) %DebugPrepareStepInIfStepping(this);
> Is this needed at almost every use of %_CallFunction?  Looks to me like there
> are more of these sites needing %DebugPrepareStepInIfStepping in the runtime
.js
> files that are unrelated to generators.

Debug::PrepareStep ignores native javascript. So in case where we call out to
user JS, that should be done. This is used in many cases, for example
Array.prototype.forEach, but in some cases we don't like Array.prototype.sort.
So far nobody complained yet, but we can always consider to add them if
demanded.

[aandrey, 2014-09-17 11:55:51]

lgtm

[Yang, 2014-09-17 12:27:25]

Committed patchset #2 (id:20001) manually as 24000 (presubmit successful).