Auto merge of #29897 - Loirooriol:clearance-prevents-margin-collapse, r=mrobinson

Prevent margins from collapsing through when separated by clearance

This fixes #29884 and improves #29896.

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---
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #29884 and improve #29896
- [X] There are tests for these changes

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components/layout_2020/flow/mod.rs

@@ -657,6 +657,7 @@ fn layout_in_flow_non_replaced_block_level(
                 collapsible_margins_in_children.collapsed_through &&
                     block_is_same_formatting_context &&
                     pbm.padding_border_sums.block == Length::zero() &&
+                    clearance == Length::zero() &&
                     block_size.auto_is(|| Length::zero()) == Length::zero() &&
                     min_box_size.block == Length::zero();
         },

tests/wpt/metadata-layout-2020/css/CSS2/floats-clear/clear-after-top-margin.html.ini

@@ -1,2 +0,0 @@
-[clear-after-top-margin.html]
-  expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/floats-clear/margin-collapse-018.xht.ini

@@ -1,2 +0,0 @@
-[margin-collapse-018.xht]
-  expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/floats-clear/margin-collapse-027.xht.ini

@@ -1,2 +0,0 @@
-[margin-collapse-027.xht]
-  expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/floats-clear/no-clearance-due-to-large-margin-after-left-right.html.ini

@@ -0,0 +1,2 @@
+[no-clearance-due-to-large-margin-after-left-right.html]
+  expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/floats-clear/remove-block-before-self-collapsing-sibling-with-clearance.html.ini

@@ -1,2 +0,0 @@
-[remove-block-before-self-collapsing-sibling-with-clearance.html]
-  expected: FAIL

tests/wpt/metadata-layout-2020/css/css-flexbox/flexbox_flow-row-wrap-reverse.html.ini

@@ -1,2 +0,0 @@
-[flexbox_flow-row-wrap-reverse.html]
-  expected: FAIL

tests/wpt/metadata-layout-2020/css/css-flexbox/flexbox_flow-row-wrap.html.ini

@@ -1,2 +0,0 @@
-[flexbox_flow-row-wrap.html]
-  expected: FAIL

tests/wpt/metadata-layout-2020/css/css-flexbox/flexbox_item-float.html.ini

@@ -1,2 +0,0 @@
-[flexbox_item-float.html]
-  expected: FAIL

tests/wpt/metadata-layout-2020/css/css-flexbox/flexbox_item-top-float.html.ini

@@ -1,2 +0,0 @@
-[flexbox_item-top-float.html]
-  expected: FAIL

tests/wpt/metadata-layout-2020/css/css-flexbox/flexbox_item-vertical-align.html.ini

@@ -1,2 +0,0 @@
-[flexbox_item-vertical-align.html]
-  expected: FAIL

tests/wpt/metadata-layout-2020/css/css-flexbox/flexbox_wrap-long.html.ini

@@ -1,2 +0,0 @@
-[flexbox_wrap-long.html]
-  expected: FAIL

tests/wpt/metadata-layout-2020/css/css-flexbox/flexbox_wrap-reverse.html.ini

@@ -1,2 +0,0 @@
-[flexbox_wrap-reverse.html]
-  expected: FAIL

tests/wpt/metadata-layout-2020/css/css-flexbox/flexbox_wrap.html.ini

@@ -1,2 +0,0 @@
-[flexbox_wrap.html]
-  expected: FAIL

tests/wpt/mozilla/meta-layout-2020/css/acid1_a.html.ini

@@ -1,2 +0,0 @@
-[acid1_a.html]
-  expected: FAIL