[LayoutNG] Don't add zero-width floats to the exclusion space.

The only thing such floats should affect is the block position of subsequent floats (float rule §5 [1] and clearance). They should not affect the inline position or inline size of subsequent floats or new formatting contexts. The spec isn't actually clear here, although the browsers agree on the above. Submitted https://github.com/w3c/csswg-drafts/issues/2312 [1] https://www.w3.org/TR/CSS22/visuren.html#float-position Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng Change-Id: Ia9e724c8a58fcb017f86f26bdf90394f09414f4e Reviewed-on: https://chromium-review.googlesource.com/919065Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org> Commit-Queue: Morten Stenshorne <mstensho@chromium.org> Cr-Commit-Position: refs/heads/master@{#537274}

[LayoutNG] Don't add zero-width floats to the exclusion space.
The only thing such floats should affect is the block position of subsequent floats (float rule §5 [1] and clearance). They should not affect the inline position or inline size of subsequent floats or new formatting contexts. The spec isn't actually clear here, although the browsers agree on the above. Submitted https://github.com/w3c/csswg-drafts/issues/2312 [1] https://www.w3.org/TR/CSS22/visuren.html#float-position Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng Change-Id: Ia9e724c8a58fcb017f86f26bdf90394f09414f4e Reviewed-on: https://chromium-review.googlesource.com/919065Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org> Commit-Queue: Morten Stenshorne <mstensho@chromium.org> Cr-Commit-Position: refs/heads/master@{#537274}
08916fed · Morten Stenshorne · Commit Bot · 4eaf12cd · 08916fed · 08916fed
Commit 08916fed authored Feb 16, 2018 by Morten Stenshorne Committed by Commit Bot Feb 16, 2018
3 changed files
--- a/third_party/WebKit/LayoutTests/FlagExpectations/enable-blink-features=LayoutNG
+++ b/third_party/WebKit/LayoutTests/FlagExpectations/enable-blink-features=LayoutNG
@@ -2362,7 +2362,6 @@ crbug.com/591099 fast/block/basic/quirk-percent-height-grandchild.html [ Failure
 crbug.com/591099 fast/block/basic/quirk-percent-height-table-cell.html [ Failure ]
 crbug.com/591099 fast/block/block-add-child-crash.html [ Crash ]
 crbug.com/591099 fast/block/block-width-recalc-with-relative-height.html [ Failure ]
-crbug.com/591099 fast/block/containing-block-negative-margins.html [ Failure ]
 crbug.com/591099 fast/block/float-avoids-padding-inline-ancestors.html [ Crash ]
 crbug.com/810335 fast/block/float/003.html [ Failure ]
 crbug.com/591099 fast/block/float/br-with-clear-2.html [ Failure ]

--- a/third_party/WebKit/LayoutTests/external/wpt/css/CSS2/floats/zero-width-floats.html
+++ b/third_party/WebKit/LayoutTests/external/wpt/css/CSS2/floats/zero-width-floats.html
+<!DOCTYPE html>
+<title>Zero width floats</title>
+<link rel="author" title="Morten Stenshorne" href="mstensho@chromium.org">
+<link rel="help" href="https://www.w3.org/TR/CSS22/visudet.html#float-width" title="10.3.5 Floating, non-replaced elements">
+<link rel="match" href="../../reference/ref-filled-green-200px-square.html">
+<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
+<div style="margin-left:50px; width:100px;">
+  <div style="float:left; width:0; height:50px;"></div>
+  <div style="float:right; clear:left; width:0; height:150px;"></div>
+  <div style="overflow:hidden; margin:0 -50px; height:100px; background:green;"></div>
+</div>
+<div style="position:relative; top:-100px; overflow:hidden; clear:both; width:200px; height:100px; background:green;"></div>
--- a/third_party/WebKit/Source/core/layout/ng/exclusions/ng_exclusion_space.cc
+++ b/third_party/WebKit/Source/core/layout/ng/exclusions/ng_exclusion_space.cc
@@ -172,6 +172,12 @@ void NGExclusionSpace::Add(scoped_refptr<const NGExclusion> exclusion) {
        std::max(right_float_clear_offset_, exclusion->rect.BlockEndOffset());
  }
+  // If the exclusion takes up no inline space, we shouldn't pay any further
+  // attention to it. The only thing it can affect is block-axis positioning of
+  // subsequent floats (dealt with above).
+  if (exclusion->rect.LineEndOffset() <= exclusion->rect.LineStartOffset())
+    return;
 #if DCHECK_IS_ON()
  bool inserted = false;
 #endif