Fix history on workspaces, where you couldn't click on old tries.

Fix history on workspaces, where you couldn't click on old tries.

Also allow editing the first and last line because you might need
to do that to fix "old" tries that are already stored in the database.
By "old" I mean yesterday.

BUG=skia:

Committed: http://code.google.com/p/skia/source/detail?r=14516

[f(malita), 2014-05-01 20:08:40]

lgtm

[jcgregorio, 2014-05-01 20:08:52]

The CQ bit was checked by jcgregorio@google.com

[commit-bot: I haz the power, 2014-05-01 20:09:09]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/jcgregorio@google.com/264833004/1

[commit-bot: I haz the power, 2014-05-01 20:17:22]

Change committed as 14516