Implement capabilities for Drag n' Drop

[jrandolf-2]

Background

Currently, Drag n' Drop is not working on any implementation of WebDriver BiDi according to WPT tests.

Problem

When a drag is initiated by a WebDriver BiDi mouse action, all inputs get ignored (yes, even mouse up), which makes the test state invalid.

Solutions

There are a couple solutions to this.

Add a dragAndDrop capability to session.CapabilitiesRequest and session.NewResult

This would hint to clients whether a given WebDriver Bidi implementation supports drag n' drop. This would imply drag n' drop must be disabled in their browser.

Pros

• The test state can never be invalid.

Cons

• Implementations may never get around to implementing drag n' drop.

Do nothing.

Pros

• Implementations must get around to implementing drag n' drop.

Cons

• The test state can be invalid.