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This is a reland of 9612f58a

The change was reverted because of failure on linux-trusty-rel due to
a mismatch in dump test result for "checkable" state.
In this reland, I added a filter @AURALINUX-DENY:checkable to fix this
test mismatch. This filter seems to accompany all other radio button dump
tests for linux platform.

Original change's description:
> A11y:Expose labels of radio & checkbox when focused.
>
> Currently, when a label is referenced by a control of type radio or
> checkbox, we set the label as ignored in the AXTree thereby excluding
> it from being perceived by ATs.
> However, for the case when the control (radio/checkbox) is a
> descendant of the label and label is focusable (tabindex="0") but
> control is to be omitted from focus (tabindex="-1"), ATs perceive
> neither the label nor the control when tabbing through the content:
>
>     <label style="display:block" tabindex="0">
>       radio button 1
>       <input type="radio" id="radio1" tabindex="-1">
>     </label>
>
>     <label style="display:block" for="radio2" tabindex="0">
>       radio button 2
>       <input type="radio" id="radio2" tabindex="-1">
>     </label>
>
>     <label style="display:block" for="checkbox1" tabindex="0">
>       checkbox 1
>       <input type="checkbox" id="checkbox1" tabindex="-1">
>     </label>
>
>     <label style="display:block" for="checkbox2" tabindex="0">
>       checkbox 2
>       <input type="checkbox" id="checkbox2" tabindex="-1">
>     </label>
>
> This change fixes the above scenario by exposing labels (referenced by
> radio or checkbox) when they are focusable. For all other cases when
> labels are referenced by radio or checkbox, we keep the existing
> behavior of ignoring the label.
>
> Note: Neither Firefox nor Edge legacy hides a label from AT when the
> label is referenced by a control. On Firefox and Edge legacy, label
> content will be read twice (focus on label and focus on control
> respectively).
> WAI-ARIA spec does not specify label should be ignored when associated
> with a radio/checkbox control.
>
> Bug: 1040210
> Change-Id: Ie7df5144dd2f0d285d97e6556adb46dcf2338f25
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1992017
> Commit-Queue: Victor Fei <vicfei@microsoft.com>
> Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#731820}

Bug: 1040210
Change-Id: I09243796ec3affe648d46ec64d7dd20e20c5893f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2002892Reviewed-by: Kurt Catti-Schmidt <kschmi@microsoft.com>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Victor Fei <vicfei@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#732931}