Improve profile menu animation

Summary:
The text sliding around feels a bit jank to me. Instead, here's an attempt at a three-part effect:

• Fade out the content of the menu (first quarter of the animation).
• Shrink the menu (half the animation).
• Fade the menu content back in (final quarter).

This isn't perfect, but feels less weird to me since the text doesn't dance?

Test Plan: clickey clickey

Reviewers: chad

Reviewed By: chad

Differential Revision: https://secure.phabricator.com/D15098