Make the mousemove event cancellable

Make the mousemove event cancellable

The mouse move event used to be non cancellable in the 90s and
when the specications changes in 2002-2003, not not everyone noticed. 

Specification:
http://www.w3.org/TR/DOM-Level-3-Events/#event-type-mousemove

Already implemented by MSIE and Opera (Presto). 
Still an open (and forgotten?) bug in Mozilla: https://bugzilla.mozilla.org/show_bug.cgi?id=704423

BUG=261449
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=157207

[Daniel Bratell, 2013-09-02 09:28:52]

abarth, can you take a look please?
It's a small fix (and, sorry to say, not super important)

[abarth-chromium, 2013-09-03 15:59:55]

This seems fine.  Can you add a link to the specification and a description of
how other browsers behave in this regard?

[Daniel Bratell, 2013-09-03 18:31:40]

On 2013/09/03 15:59:55, abarth wrote:
> This seems fine.  Can you add a link to the specification and a description of
> how other browsers behave in this regard?

Sure. The bug has a link to the spec (and some discussion) that says that this
was changed (without tracking) some ten years ago and MSIE (and Presto)
implements it per spec. Mozilla has an open bug which they've forgotten about
and we have this. Should I add something like this to the code?

[abarth-chromium, 2013-09-03 21:08:12]

On 2013/09/03 18:31:40, Daniel Bratell wrote:
> Should I add something like this to the code?

That good information to add to the Description field.  That way it will be
available in the commit history.

[abarth-chromium, 2013-09-03 21:08:32]

LGTM w/ updated description

[commit-bot: I haz the power, 2013-09-04 06:08:57]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/bratell@opera.com/23463012/1

[commit-bot: I haz the power, 2013-09-04 08:11:11]

Change committed as 157207