Fix iossim to only check for crashes from the simulated app.

When attempting to check for crashes, iossim was not taking into
account the ID or PID of the simulated app so if *any* app crashed
while the simulated app was running, iossim would report that the
simulated app crashed and return non-zero status code.

BUG=None

Review URL: https://codereview.chromium.org/431093003

git-svn-id: http://src.chromium.org/chrome/trunk/src/testing@286898 4ff67af0-8c30-449e-8e8b-ad334ec8d88c