Raised buttons with colors are not following spec on focus

[Maistho]

Bug, feature request, or proposal:

Bug

What is the expected behavior?

Text color of raised buttons with color does not change on focus
Background-color of raised buttons with color changes on focus

What is the current behavior?

Text color of raised buttons with color changes on focus
Background-color of raised buttons with color does not on focus

What are the steps to reproduce?

Here is a plunker that shows the issue
http://plnkr.co/edit/36A2DKgGGP4PtFfBrBtO?p=preview

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

It should follow the spec

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

Latest master has this issue

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