Bug 1701112 [wpt PR 28254] - [TablesNG] Clusterfuzz crash for empty tables, a=testonly

Automatic update from web-platform-tests
[TablesNG] Clusterfuzz crash for empty tables

ComputeMaximumNonMergeableColumnCount was incorrectly
returning 1 even if all columns were mergeable.

Bug: 1192572,1193011
Change-Id: I88ab425fae7bd72da264b99009df6b72ddbb7439
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2787668
Reviewed-by: Koji Ishii <kojii@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Aleks Totic <atotic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#866960}

--

wpt-commits: ea20021cad266cdf743a396cc8179991cdec7e87
wpt-pr: 28254

testing/web-platform/tests/css/css-tables/crashtests/empty_table_with_cols.html

@@ -0,0 +1,3 @@
+<table style="border:1px solid black;border-collapse: collapse">
+  <colgroup >
+    <tr></tr>