Update legacy-mrow-like-elements-001.html to expect display `block math'
Additionally update the test assert description to refer to the
computed display value rather than the attribute.
Bug: 372512083
Change-Id: I9e940e79a64482554f6132388b2566b7170a7671
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5941615
Reviewed-by: Frédéric Wang fwang@igalia.com
Reviewed-by: Rob Buis rbuis@igalia.com
Commit-Queue: Frédéric Wang fwang@igalia.com
Cr-Commit-Position: refs/heads/main@{#1371359}