V8 Buildbot: Use gitles poller for client.v8 in svn mode.
V8 Buildbot: Use gitles poller for client.v8 in svn mode.

TBR=agable@chromium.org
BUG=391687

Review URL: https://codereview.chromium.org/660733002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@292481 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build