Insert path-to-bison at head, rather than tail

Per https://groups.google.com/a/chromium.org/d/msg/chromium-dev/HNwefOwoWwU/5GRlD9gATscJ

R=thakis@chromium.org
BUG=123026

Review URL: https://codereview.chromium.org/149733002

git-svn-id: svn://svn.chromium.org/blink/trunk@166066 bbb929c8-8fbe-4397-9dbb-9b2b20218538