We needed to set the CWD for the mock ICD as well.

Bug: angleproject:2604
Change-Id: I1d285c478030056360fd2dceca78e231ac321219
Reviewed-on: https://chromium-review.googlesource.com/1169426Reviewed-by: Omar El Sheikh <theoking@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>