[LayoutNG] Don't allow breaks at the start of a fragmentainer.

We had this almost right, but failed when there was a break with low appeal inside a child. Bug: 829028 Change-Id: I67c0d07db85b8de6d9ac3f685263fb1d3b490760 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1940273 Reviewed-by: Koji Ishii <kojii@chromium.org> Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org> Commit-Queue: Morten Stenshorne <mstensho@chromium.org> Cr-Commit-Position: refs/heads/master@{#719919}
tkntjsdw · Nov 28, 2019 · d7994d6 · d7994d6
1 parent 7d567a5
commit d7994d6
Showing 1 changed file with 10 additions and 0 deletions.
diff --git a/css/css-break/tall-break-inside-avoid-at-start.html b/css/css-break/tall-break-inside-avoid-at-start.html
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+<!DOCTYPE html>
+<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
+<link rel="help" href="https://www.w3.org/TR/css-break-3/#unforced-breaks">
+<link rel="match" href="../reference/ref-filled-green-100px-square.xht">
+<meta name="assert" content="Cannot break before a child if we're at the block-start of a fragmentainer">
+<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
+<div style="columns:2; column-fill:auto; column-gap:0; width:100px; height:100px; background:red;">
+  <div></div>
+  <div style="break-inside:avoid; height:200px; background:green;"></div>
+</div>