It breaks upstream webkit and nacl. I'll make then both use --jobs 1 before
relanding.

TBR=dpranke@chromium.org
BUG=
TEST=


Review URL: http://codereview.chromium.org/7833051

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@99761 0039d316-1c4b-4281-b951-d872f2087c98