MdDialog opens additional dialogs when enter or space key is pressed during opening transition

[peterdavey]

Bug, feature request, or proposal:

Bug

What is the expected behavior?

The initial dialog being opened should close returning the user to the state before dialog open was triggered

What is the current behavior?

After each press of either enter or spacebar a new dialog is opened on top of the initial dialog. The users is then required to close all these windows

What are the steps to reproduce?

Create an event causing an mddialog to open then immediately press enter or space key multiples times until this opening transition is finished.

This behaviour can be viewed in the current example page https://material.angular.io/components/dialog/examples

What is the use-case or motivation for changing an existing behavior?

Which versions of Angular, Material, OS, TypeScript, browsers are affected?

angular: 4.3.3, material: 2.0.0-beta.8, typescript: 2.4.2, browsers checked firefox 54.0.1 (64-bit) and chrome 60.0.3112.78 (Official Build) (64-bit)

Is there anything else we should know?

[crisbeto]

Should be sorted one by #5769 in the next release.

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}