QUnit: assertThrows without regex matching for description

[sejvlond]

At the moment description of an exception is being tested for regular expression match - this is not documented and it is very hard to write it properly for descriptions with special chars like ( / ? { [ ...

Solution would be to add a new function like assertThrowsExact? with equality comparison for description, or add an optional flag to the existing function?

For sure to update the current documentation.

[davidnich]

@sejvlond sounds good - note that I removed the module tag, as we generally only use that for external modules (ex: module-xml)