Original: microsoft/BotFramework-Emulator#1978

User Impact:
Users who depends on screen reader will get confuse if screen reader is not providing the descriptive information when focus is on "New Messages" button.

Test Environment:
OS: Version: 1903(OS Build 18956.1000)
URL: https://ms.portal.azure.com/#@microsoft.onmicrosoft.com/resource/subscriptions/8d5ceb22-44c7-4367-bfc6-07378096e055/resourceGroups/sddsddd/providers/Microsoft.BotService/botServices/avinash/channels
Browser: Edge
Screen Reader: Narrator

Pre requisite:
create new web app bot.

Repro Steps:

1. Turn on Narrator.
2. Open https://ms.portal.azure.com/#@microsoft.onmicrosoft.com/resource/subscriptions/8d5ceb22-44c7-4367-bfc6-07378096e055/resourceGroups/sddsddd/providers/Microsoft.BotService/botServices/avinash/channels in Edge.
3. Navigate to already created web app bot.
4. Navigate to "Test in Web Chat" element and activate it.
5. Now "Test" screen will be displayed.
6. Navigate to "New Messages" button and verify whether screen reader is providing the descriptive information when focus is on "New Messages" button.

Actual Result:
Screen reader is not providing the descriptive information when focus is on "New Messages" button.
Screen reader is reading as "New Messages button"

Expected Result:
Screen reader should provide the descriptive information ,when focus is on "New Messages" button.
Screen reader should read as "New Messages button, hit ENTER to see the new messages".

Note:
Same issue repro with NVDA also.

MAS Reference
https://microsoft.sharepoint.com/:w:/r/teams/msenable/_layouts/15/WopiFrame2.aspx?sourcedoc=%7B54f28d1f-a2d1-4dcd-84e1-5c9b87e8aba4%7D&cid=ea080456-8c71-4c66-b1f0-9a2a20e08097

Attachment:
New Messages button descriptive.zip