If a fragment is too tall, just break before it.

There was some old code that wasn't needed anymore, and it was causing
trouble for nested multicol. We need to break before a multicol
container if it doesn't fit. The column layout algorithm always tries to
limit the block size of an inner multicol container, so that it will fit
in the outer fragmentation context. If that's not possible, though, we
need to break before it and retry in the next outer fragmentainer.

So for multicol container children we needed the code path that we
previously only ran for child.IsMonolithic(), but we can in fact always
do that (if it doesn't fit, and we're allowed to break, let's break!),
so just delete the unnecessary code, and fix 5 tests. :)

Bug: 829028
Change-Id: I93b6b10c8b427055e69f094b460c13fa68a49fa6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2575031
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834585}

third_party/blink/renderer/core/layout/ng/ng_fragmentation_utils.cc

@@ -639,38 +639,20 @@ bool MovePastBreakpoint(const NGConstraintSpace& space,
         builder->SetBreakAppeal(appeal_inside);
       return true;
     }
-  } else {
-    bool need_break;
-    if (refuse_break_before) {
-      need_break = false;
-    } else if (child.IsMonolithic()) {
-      // If the monolithic piece of content (e.g. a line, or block-level
-      // replaced content) doesn't fit, we need a break.
-      need_break = fragment.BlockSize() > space_left;
-    } else {
-      // If the block-offset is past the fragmentainer boundary (or exactly at
-      // the boundary), no part of the fragment is going to fit in the current
-      // fragmentainer. Fragments may be pushed past the fragmentainer boundary
-      // by margins. We shouldn't break before a zero-size block that's exactly
-      // at a fragmentainer boundary, though.
-      need_break = space_left < LayoutUnit() ||
-                   (space_left == LayoutUnit() && fragment.BlockSize());
-    }
-
-    if (!need_break) {
-      if (child.IsBlock() && builder) {
-        // If this doesn't happen, though, we're tentatively not going to break
-        // before or inside this child, but we'll check the appeal of breaking
-        // there anyway. It may be the best breakpoint we'll ever find. (Note
-        // that we only do this for block children, since, when it comes to
-        // inline layout, we first need to lay out all the line boxes, so that
-        // we know what do to in order to honor orphans and widows, if at all
-        // possible.)
-        UpdateEarlyBreakAtBlockChild(space, To<NGBlockNode>(child),
-                                     layout_result, appeal_before, builder);
-      }
-      return true;
+  } else if (refuse_break_before || fragment.BlockSize() <= space_left) {
+    // The child either fits, or we are not allowed to break. So we can move
+    // past this breakpoint.
+    if (child.IsBlock() && builder) {
+      // We're tentatively not going to break before or inside this child, but
+      // we'll check the appeal of breaking there anyway. It may be the best
+      // breakpoint we'll ever find. (Note that we only do this for block
+      // children, since, when it comes to inline layout, we first need to lay
+      // out all the line boxes, so that we know what do to in order to honor
+      // orphans and widows, if at all possible.)
+      UpdateEarlyBreakAtBlockChild(space, To<NGBlockNode>(child), layout_result,
+                                   appeal_before, builder);
     }
+    return true;
   }
 
   // We don't want to break inside, so we should attempt to break before.

third_party/blink/web_tests/TestExpectations

@@ -1073,13 +1073,10 @@ crbug.com/1066629 virtual/layout_ng_block_frag/fast/multicol/hit-test-translate-
 crbug.com/829181 virtual/layout_ng_block_frag/fast/multicol/infinitely-tall-content-in-outer-crash.html [ Skip ]
 crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/insane-column-gap.html [ Failure ]
 crbug.com/1066626 virtual/layout_ng_block_frag/fast/multicol/layers-split-across-columns.html [ Failure ]
-crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/line-too-tall-for-second-outer-row.html [ Failure ]
 crbug.com/1066626 virtual/layout_ng_block_frag/fast/multicol/mixed-opacity-fixed-test.html [ Failure ]
 crbug.com/1079031 virtual/layout_ng_block_frag/fast/multicol/mixed-opacity-test.html [ Crash Failure ]
-crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/nested-auto-height-short-first-row.html [ Failure ]
 crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/nested-balanced-inner-column-count-1-with-forced-break.html [ Failure ]
 crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/nested-short-first-row-extra-tall-line.html [ Failure ]
-crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/nested-short-first-row-unsplittable-block.html [ Failure ]
 crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/nested-very-tall-inside-short-crash.html [ Skip ]
 crbug.com/1058792 virtual/layout_ng_block_frag/fast/multicol/nested-with-composited-and-multicol-crash.html [ Crash ]
 crbug.com/1131125 virtual/layout_ng_block_frag/fast/multicol/nested-with-forced-breaks-in-eariler-rows.html [ Failure ]
@@ -1096,8 +1093,6 @@ crbug.com/1079031 virtual/layout_ng_block_frag/fast/multicol/positioned-outside-
 crbug.com/1079031 virtual/layout_ng_block_frag/fast/multicol/positioned-split.html [ Failure ]
 crbug.com/1058792 virtual/layout_ng_block_frag/fast/multicol/span/invalid-spanner-in-transform.html [ Failure Crash ]
 crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/span/outer-column-break-after-inner-spanner-2.html [ Failure ]
-crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/span/outer-column-break-after-inner-spanner-and-float.html [ Failure ]
-crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/span/outer-column-break-after-inner-spanner.html [ Failure ]
 crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/span/preferred-widths-with-column-content.html [ Failure ]
 crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/span/spanner-with-margins-between-margins.html [ Failure ]
 crbug.com/829028 virtual/layout_ng_block_frag/fast/multicol/span/trailing-margin-before-spanner.html [ Failure ]