V8 Buildbot: Revert removing primary v8 repository from chromium builds.
V8 Buildbot: Revert removing primary v8 repository from chromium builds.

Even though safe sync seemed to work now, the visual correlation from v8 revisions to builds doesn't fit anymore.

Review URL: https://chromiumcodereview.appspot.com/19934010

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@213376 0039d316-1c4b-4281-b951-d872f2087c98

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