The problem? These names are effectively useless for determining the extent of test coverage. (Assume arguendo that all these files were properly located in directories specific to a feature being tested, for example in a hypothetical layout/reftests/list-item directory for the two aforementioned tests, to make it reasonable to scan the coverage of a particular feature.) If I want to know what corner cases are being tested, I have to read each test and corresponding bug individually, a tedious task.

The solution? Name your test files descriptively. For example, in the above case, a better name might perhaps be marker-position-for-list-item-containing-block-with-margins.html.

Okay, this will make it easier for random readers at unknown points in the future, but is there anything in it for you, the test author? There is: you may endear yourself to reviewers. For example, dbaron decided, based upon the names I gave to test files in the recent patch I wrote to implement background-size (and upon a handful of comments in the list of tests itself), that my patch’s tests were adequate and didn’t need a long, tedious review of each one:

The reftest.list looks good based on the names of the tests and the
comments; I don't see the need to review the tests themselves.

In conclusion: DON’T name your test files based upon bug numbers, and DO name them based upon the particular scenario that they test. Readers will and reviewers may thank you.