1725696 - WPT test css/css-multicol/parsing/column-rule-valid.html fails because Firefox is too verbose when serializing `column-rule` shorthand (unnecessarily including default values of unset subproperties)

Status: NEW

(Core :: CSS Parsing and Computation, defect)

Description

[Daniel Holbert [:dholbert]]

STR:

1. Run the test https://wpt.live/css/css-multicol/parsing/column-rule-valid.html

ACTUAL RESULTS:
The test fails with these errors:

assert_equals: serialization should be canonical expected "10px" but got "10px none currentcolor"
assert_equals: serialization should be canonical expected "dotted" but got "medium dotted currentcolor"
assert_equals: serialization should be canonical expected "red" but got "medium none red"

EXPECTED RESULTS:
Test should pass; we should serialize using the shortest value, as the test expects.

Here are some simpler/reduced STR:
(1) View this testcase:

data:text/html,<div id="foo" style="column-rule: red"><script>alert(foo.style.columnRule)</script>

ACTUAL RESULTS:
The alert reports that the serialized style is "medium none red"

EXPECTED RESULTS:
Should report "red".