Adding parser layout test for whitespace around comma in argument list

Imported webkit testcase from here:
https://bugs.webkit.org/show_bug.cgi?id=77773

Appears issues is already fixed in blink, so no code changes required.

BUG=231630

Review URL: https://codereview.chromium.org/178943002

git-svn-id: svn://svn.chromium.org/blink/trunk@167737 bbb929c8-8fbe-4397-9dbb-9b2b20218538