graphics_WebGL*: clean up http server after test is done

Calling StopLocalServers() after running the test to properly shut
down the http server.

Signed-off-by: Ricky Liang <jcliang@chromium.org>

BUG=None
TEST=Run `test_that --board <board> --fast <dut> graphics_WebGLAquarium`
     and verify that the http server is shut down after the test.

Change-Id: I1a488ed57724ede48a3a052bc7fd9f1fa569ffcf
Reviewed-on: https://chromium-review.googlesource.com/327352
Commit-Ready: Ilja Friedel <ihf@chromium.org>
Tested-by: Ricky Liang <jcliang@chromium.org>
Reviewed-by: Ilja Friedel <ihf@chromium.org>
2 files changed