Disabled select element should not fire onchange event.

Disabled select element should not fire onchange event.

After http://trac.webkit.org/changeset/140286, select elements can scroll
whether they are disabled or not. While they scroll, they also change the
selected item.
This patch allows the select element to scroll, but does not change the selection if the select element is disabled.

BUG=215494
TEST=fast/forms/select/listbox-disabled-no-autoscroll.html

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=149951

[yael.aharon1, 2013-05-07 22:25:50]

Can you please review? thanks

[tkent, 2013-05-07 22:35:29]

We should revert your previous change in HTMLSelectElement::listBoxOnChange.

> TEST=fast/forms/select/listbox-disabled-scroll-no-onchange.html

The test should be updated so that it verifies selection state is not changed.

[yael.aharon1, 2013-05-07 23:07:00]

On 2013/05/07 22:35:29, tkent wrote:
> We should revert your previous change in HTMLSelectElement::listBoxOnChange.
> 
> > TEST=fast/forms/select/listbox-disabled-scroll-no-onchange.html
> 
> The test should be updated so that it verifies selection state is not changed.

Please note that the previous change is still needed because without it,
HTMLSelectElement::listBoxOnChange() will generate a onchange event, because
m_lastOnChangeSelection is empty.

[tkent, 2013-05-07 23:37:48]

listBoxOnChange is called after status update by user actions, and shouldn't be
called for disabled <select> basically.  Probably we need isDisabledFormControl
check in another place.

[yael.aharon1, 2013-05-08 02:33:25]

On 2013/05/07 22:35:29, tkent wrote:
> We should revert your previous change in HTMLSelectElement::listBoxOnChange.
> 
> > TEST=fast/forms/select/listbox-disabled-scroll-no-onchange.html
> 
> The test should be updated so that it verifies selection state is not changed.

I spent a lot of time today trying to create a test that causes the autoscroll
timer to fire. So far, I could not. The mouse events are collected and replayed
after everything else, so the timeouts that I built into the tests did not do
anything and the autoscroll timer never fired. Is there a way to space out the
mouse events, so that the timer can fire?

[yael.aharon1, 2013-05-08 03:30:27]

I moved the check for isDisabledFormControl() to RenderListBox, so its checks if
the select is enabled before calling listBoxOnChange().

Also, I found a way to construct a test where the selection changes without this
patch, but doesn't change with it.
Could you please review? thanks!

[tkent, 2013-05-08 03:57:54]

lgtm.
Thank you!

[commit-bot: I haz the power, 2013-05-08 11:34:52]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/yael.aharon@intel.com/14996003/6001

[commit-bot: I haz the power, 2013-05-08 12:28:47]

Change committed as 149951