autocomplete: escape always cleans text despite md-escape-options

[clshortfuse]

Actual Behavior:
Text is cleared always.
If md-escape-options is set to not clear text, it shouldn't

CodePen (or steps to reproduce the issue): *
http://codepen.io/shortfuse/pen/dXWNpy

Angular Versions: *

• Angular Version: 1.5.5
• Angular Material Version: master

Additional Information:

• Browser Type: * Chrome
• Browser Version: * v52
• OS: * ChromeOS

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This is because of the input field type='search'. There should be a preventDefault when escape is pressed since we'll be handling that interaction, and not the browser.