They are transformed by the scanner to the identifier `inline`, which is how the parser identifies it. This solves the comment problem, but it results in a funny side effect. Now, in inline mode, /*pragma inline*/ will always be the identifier `inline`, therefore this is valid:
integer /*pragma inline*/ = 5;
llOwnerSay((string)inline); // will say 5
Not overly elegant, but better than making up a specific token or declaring comments as tokens or the like.
This test suite has been in use for a long time now, in place of the obsolete and unmanageable testparser.py and testfuncs.py. It verifies the complete optimizer output to stdout and stderr, to ensure that the output matches the expectations.
See unit_tests/README.txt for more info.