Searchbox proposals go async (and some cosmetic fixes).

Searchbox proposals go async (and some cosmetic fixes).

The biggie here is the migration to an asynchronous update of type proposals.  Beyond that, there are a few cosmetic fixes as well:

  * search result table height is now computed based on contents (less whitespace)
  * removed undesired separator after last proposal entry in the table
Committed: https://code.google.com/p/dart/source/detail?r=8358

[danrubel, 2012-06-05 22:07:12]

lgtm