[Qt] Fix regression to test-webkitpy.
https://bugs.webkit.org/show_bug.cgi?id=114368

Reviewed by Ryosuke Niwa.

* Scripts/webkitpy/layout_tests/port/factory.py:
(PortFactory._default_port): Return qt-linux instead of chromium-linux as default port for linux/freebsd.
(PortFactory.get): Remove obsolete chromium port related code.
* Scripts/webkitpy/layout_tests/port/mac.py:
(MacPort.default_child_processes): Prevent type error if can't determine total memory.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@148126 268f45cc-cd09-0410-ab3c-d52691b4dbfc