md-select does not inherit custom theme

[haneev]

Using a md-select in a md-theme section, does not inherit the theme. For example, using a dark theme based on light-green, md-select is using the default theme (blue) instead of the light-green.

See this codepen: http://codepen.io/anon/pen/RPPoZg

The inputs are using the correct theme, however md-select is using the default theme. This is not expected.

[mprentic-harris]

Looks like a dup of #2483?