[Masonry] Add computed value test for repeat(auto-fill, auto)

Add test for serialization of `repeat(auto-fill, auto)` in grid-lanes.

This closes out the remaining serialization tasks - flow-tolerance,
grid-lanes-direction, and grid-lanes-pack serialization are already
working with existing test coverage.

Bug: 343257585
Change-Id: Icc4e000906e234c419a01acef2fbdef838a14b33
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7812608
Commit-Queue: Yanling Wang <yanlingwang@microsoft.com>
Reviewed-by: Celeste Pan <celestepan@microsoft.com>
Reviewed-by: Alison Maher <almaher@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#1627039}

Author: yanlingwang23

css/css-grid/grid-lanes/grid-lanes-grid-template-columns-computed-withcontent.html

@@ -72,14 +72,18 @@
           '30px 54px 54px 54px 54px 54px');
   test_computed_value("grid-template-columns", '[] 150px [] 1fr []', '150px 150px');
 
-  // <auto-repeat> = repeat( [ auto-fill | auto-fit ] , [ <line-names>? <fixed-size> ]+ <line-names>? )
+  // <auto-repeat> = repeat( [ auto-fill | auto-fit ] , [ <line-names>? [ <fixed-size> | auto ] ]+ <line-names>? )
   test_computed_value("grid-template-columns", 'repeat(auto-fill, 200px)', '200px');
   test_computed_value("grid-template-columns", 'repeat(auto-fit, [one] 20%)',
           '[one] 60px [one] 0px [one] 0px [one] 0px [one] 0px');
   test_computed_value("grid-template-columns", 'repeat(auto-fill, minmax(100px, 5fr) [two])',
           '100px [two] 100px [two] 100px [two]');
   test_computed_value("grid-template-columns", 'repeat(auto-fit, [three] minmax(max-content, 6em) [four])',
           '[three] 240px [four]');
+  test_computed_value("grid-template-columns", 'repeat(auto-fill, auto)',
+          '30px 30px 30px 30px 30px 30px 30px 30px 30px 30px');
+  test_computed_value("grid-template-columns", 'repeat(auto-fit, auto)',
+          '300px 0px 0px 0px 0px 0px 0px 0px 0px 0px');
 
   // <auto-track-list> =
   // [ <line-names>? [ <fixed-size> | <fixed-repeat> ] ]* <line-names>?