Changed the Problems view to sort the description column by the description text first, and file ...

Changed the Problems view to sort the description column by the description text first, and file and line information second.

The default sort column has been changed to the Location (file+line) column, in order to retain the preferred initial sort order - severity, file, line, description.
Committed: https://code.google.com/p/dart/source/detail?r=1719

[devoncarew, 2011-11-21 19:47:30]

Fix for http://code.google.com/p/dart/issues/detail?id=458.

[keertip, 2011-11-21 20:06:33]

lgtm

[pquitslund, 2011-11-21 21:26:51]

LGTM