Get rid of chromium_swarm_tests that was added by error in r205976.
Get rid of chromium_swarm_tests that was added by error in r205976.

It's because test_isolation_mode may not be set properly by default, in
particular on OSX. This GYP_DEFINES is set dynamically in
RunHooksShell.setupEnvironment() depending if needed or not.

TBR=iannucci@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/16922005

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@206053 0039d316-1c4b-4281-b951-d872f2087c98

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