Accessibility: Dropdown role is combobox which is incorrect

[rickyp-ms]

Bug Report

• Package version(s): 4.21.3
• Browser and OS versions: All

Priorities and help requested (not applicable if asking question):

Are you willing to submit a PR to fix? Yes

Requested priority: Normal

Products/sites affected: tasks.office.com

Describe the issue:

Accessibility review opened a bug on us...
"For the Bucket/Progress Combo box, Voice Over announces "Type text or, to display a list of choices , press Ctrl+option+Space. The part "Type text" is improper and cannot be processed."

Our implementation of the Bucket dropdown looks like this:

    <Dropdown
        className="taskBucket"
        label={ TaskDetailsEditorResx.TaskBucketLabel }
        options={ this.getBucketList(task) }
        onChanged={ this.onBucketChanged.bind(this) }
        />

Digging through Fabric I did notice the role="combobox" on dropdown. My guess is it may supposed to be role="menu" so that screen readers do not say Type text.

Another choice is if the user is focused on the component and starts typing the name of a list item, we should select that list item. I think the select in browsers do this by default.

Actual behavior:

Screen readers read out incorrect information

Expected behavior:

Depends if we want to support typing to select an item or just change the role.