[Mac] Log some NSException info with crash dumps.
[Mac] Log some NSException info with crash dumps.

Adds two breakpad keys.  "firstexception" will store the name and
reason for the first NSException caught by the event loop.
"lastexception" will store the same for the last one seen before
crashing.

http://crbug.com/24462
TEST=Hard to test without known exceptions to handle.

Review URL: http://codereview.chromium.org/275008

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@29349 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser