Add routine for checking startTime when start the next utterance in handleSpeakingCompleted()

Add routine for checking startTime when start the next utterance in handleSpeakingCompleted()

Same functions are called twice when calling speak() function repeatedly like current issue.
This issue is caused by asynchronous call.

So, I add routine for checking startTime in handleSpeakingCompleted() that is for preventing call twice.

BUG=367535
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=178344

[deejay, 2014-07-16 11:58:00]

PTAL.

[haraken, 2014-07-16 12:01:46]

Can we add a test case?

[deejay, 2014-07-16 15:17:21]

On 2014/07/16 12:01:46, haraken wrote:
> Can we add a test case?

I think that it is difficult to make a layout test. 
Instead of TC, we can verify manually through JS script code in issue list
(BUG=367535).
Also I had a test complete using it.

[haraken, 2014-07-16 15:29:32]

On 2014/07/16 15:17:21, djmix.kim wrote:
> On 2014/07/16 12:01:46, haraken wrote:
> > Can we add a test case?
> 
> I think that it is difficult to make a layout test. 
> Instead of TC, we can verify manually through JS script code in issue list
> (BUG=367535).
> Also I had a test complete using it.

ok, it looks hard to add tests to count # of speaks.

LGTM.

[deejay, 2014-07-17 07:45:36]

The CQ bit was checked by djmix.kim@samsung.com

[commit-bot: I haz the power, 2014-07-17 07:46:32]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/djmix.kim@samsung.com/398683005/1

[commit-bot: I haz the power, 2014-07-17 09:18:53]

Change committed as 178344