Snackbar: Queued messages modify current message

[dpraul]

What MDC-Web Version are you using?

0.16.0

What browser(s) is this bug affecting?

Chrome 59.0.3071.115

What OS are you using?

Windows 10

What are the steps to reproduce the bug?

1. Run demo server (bud is also present on current live demo)
2. Navigate to /snackbar.html
3. Press "Show"
4. Before the snackbar hides, change one of the input parameters (i.e. change "Message Text" to "hi")
5. Click "Show" again

What is the expected behavior?

The current snackbar displays until timeout or until the action is clicked (when dismissesOnAction is true), then a new snackbar shows with the updated input.

What is the actual behavior?

The current snackbar is modified with the new input parameters, it hides, and then a new snackbar appears with the identical (updated) information.