Update list of V8 try bots.

R=jarin@chromium.org
TBR=jarin@chromium.org
BUG=353487
LOG=n

Review URL: https://codereview.chromium.org/219493002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20365 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

PRESUBMIT.py

@@ -103,6 +103,7 @@ def CheckChangeOnCommit(input_api, output_api):
 def GetPreferredTryMasters(project, change):
   return {
     'tryserver.v8': {
+      'v8_linux_rel': set(['defaulttests']),
       'v8_mac_rel': set(['defaulttests']),
       'v8_win_rel': set(['defaulttests']),
     },