graphics_o3dselenium: change all return error.* to raise error.*

The former is a wrong way to do it and in fact doesn't do anything.

BUG=none
TEST=run it

Change-Id: I583aee7afa55a299576bb5652ac61fab5b6fd351

R=zmo@chromium.org

Review URL: http://codereview.chromium.org/6719025
1 file changed