The failure handler (test/failure_handler) runs a number of commands when it detects a timeout in one of the tests. On OS X some of these commands require "Developer mode" (like getting a core file). If "Developer mode" is not enabled, the tools will open a modal dialog. This is problematic when running automated test. The dialog will also prevent other tests from completing.

Failure handler should be modified to check if "Developer mode" is enabled before running commands that require it.

Checking for "Developer mode" can be done with "DevToolsSecurity --status"