Fix listbox selections with only disabled options.

Fix listbox selections with only disabled options.

blink::HTMLSelectElement::updateListBoxSelection relies on that
a list contains at least one item and that the index of any active
selection anchor is a nonnegative integer. However, if we have a
selection with only a disabled option then this assumption and the
checking assertion fail. But since updateListBoxSelection is
aware of such situations we can simply remove the assertion check
and use integers as indices instead of the unsigned variables.

BUG=436454
R=keishi

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=186781

[reni, 2014-11-25 15:39:45]

rhodovan.u-szeged@partner.samsung.com changed reviewers:
+ keishi@chromium.org, timloh@chromium.org

[Timothy Loh, 2014-11-25 23:14:00]

I haven't worked with this area of the code base before, removing myself from
the reviewer list.

[Timothy Loh, 2014-11-26 00:43:16]

timloh@chromium.org changed reviewers:
- timloh@chromium.org

[reni, 2014-12-01 19:06:39]

Could someone take a look at this please?

[keishi, 2014-12-02 02:40:13]

https://codereview.chromium.org/761463002/diff/1/Source/core/html/HTMLSelectE...
File Source/core/html/HTMLSelectElement.cpp (right):

https://codereview.chromium.org/761463002/diff/1/Source/core/html/HTMLSelectE...
Source/core/html/HTMLSelectElement.cpp:617: if (m_activeSelectionAnchorIndex <
0)
I think updateListBoxSelection should just be able to handle the no active
selection case.
We can just remove the ASSERT and changed the unsigned variables to ints.

[keishi, 2014-12-09 13:58:42]

The CQ bit was checked by keishi@chromium.org

[keishi, 2014-12-09 13:58:43]

lgtm

[commit-bot: I haz the power, 2014-12-09 13:58:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/761463002/20001

[reni, 2014-12-09 14:32:01]

On 2014/12/09 13:58:43, keishi wrote:
> lgtm

Thanks!

[commit-bot: I haz the power, 2014-12-09 14:43:47]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=186781