Remove some known_crashes.txt entries that are no longer needed. - 72796, 83674 and 83676 have not occurred recently (as far as back as we have builder logs) - 83657 has been fixed
Remove some known_crashes.txt entries that are no longer needed.
- 72796, 83674 and 83676 have not occurred recently (as far as back as we have builder logs)
- 83657 has been fixed

BUG=72796,83657,83676,83674
TEST=no
R=mattm@chromium.org

Review URL: http://codereview.chromium.org/7523034

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@94805 0039d316-1c4b-4281-b951-d872f2087c98

yitian134/chromium,gavinp/chromium,ropik/chromium,ropik/chromium,adobe/chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,yitian134/chromium,ropik/chromium,ropik/chromium,gavinp/chromium,ropik/chromium,adobe/chromium,gavinp/chromium,adobe/chromium,adobe/chromium,yitian134/chromium,adobe/chromium,gavinp/chromium,ropik/chromium,ropik/chromium,gavinp/chromium,gavinp/chromium,yitian134/chromium,gavinp/chromium,ropik/chromium,adobe/chromium,gavinp/chromium,ropik/chromium,yitian134/chromium,gavinp/chromium,yitian134/chromium,yitian134/chromium,adobe/chromium,yitian134/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,adobe/chromium