Identify command line flags only available to certain shells

[beverloo]

http://peter.sh/experiments/chromium-command-line-switches/

Certain flags, e.g. --run-layout-test, are only available in certain shells rather than in all of Chrome. This could be determined based on the path of the file, which starts with //content/shell/ in case of the aforementioned flag.

Identifying them using either a new conditional, or a separate new flag, would increase clarify about the applicability.

Thanks to @Jip-Hop for the suggestion :-).