Do not hoist floated fragments

Instead of hoisting floated fragments to be siblings of the fragment
created by their containing block formatting context, keep them in
"normal" fragment tree position and adjust their positioning to be
relative to the containing block. This means that float fragments follow
the existing invariants of the fragment tree and properly handle hit
testing, painting order, and relative positioning.

The tradeoff here is more complexity tracking the containing block
offsets from the block formatting context (including handling collapsed
margins), but less complexity dealing with hoisting / shared ownership
in addition to the correctness benefits.

Some tests are failing now because this change revealed some additional
shortcomings with clearing block formatting context content size past
the end of their contained floats. This will be fixed in a followup
change.

Co-authored-by: Oriol Brufau <obrufau@igalia.com>

tests/wpt/metadata-layout-2020/css/CSS2/floats-clear/clear-on-child-with-margins-2.html.ini

@@ -0,0 +1,2 @@
+[clear-on-child-with-margins-2.html]
+  expected: FAIL

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

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

tests/wpt/metadata-layout-2020/css/CSS2/floats/float-no-interpolation.html.ini

@@ -8,18 +8,6 @@
   [CSS Transitions with transition: all: property <float> from [initial\] to [right\] at (0.3) should be [right\]]
     expected: FAIL
 
-  [CSS Animations: property <float> from [initial\] to [right\] at (0.5) should be [right\]]
-    expected: FAIL
-
-  [CSS Animations: property <float> from [initial\] to [right\] at (0.6) should be [right\]]
-    expected: FAIL
-
-  [CSS Animations: property <float> from [initial\] to [right\] at (1) should be [right\]]
-    expected: FAIL
-
-  [CSS Animations: property <float> from [initial\] to [right\] at (1.5) should be [right\]]
-    expected: FAIL
-
   [Web Animations: property <float> from [initial\] to [right\] at (-0.3) should be [initial\]]
     expected: FAIL
 

tests/wpt/metadata-layout-2020/css/CSS2/floats/float-root.html.ini

@@ -1,2 +1,2 @@
 [float-root.html]
-  expected: TIMEOUT
+  expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/floats/float-under-flatten-under-preserve-3d.html.ini

@@ -1,2 +0,0 @@
-[float-under-flatten-under-preserve-3d.html]
-  expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/floats/hit-test-floats-001.html.ini

@@ -1,3 +0,0 @@
-[hit-test-floats-001.html]
-  [hit-test-floats-001]
-    expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/floats/hit-test-floats-004.html.ini

@@ -1,3 +0,0 @@
-[hit-test-floats-004.html]
-  [Miss float below something else]
-    expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/floats/hit-test-floats-005.html.ini

@@ -1,3 +0,0 @@
-[hit-test-floats-005.html]
-  [Miss clipped float]
-    expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/floats/new-fc-beside-adjoining-float.html.ini

@@ -1,2 +0,0 @@
-[new-fc-beside-adjoining-float.html]
-  expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/floats/new-fc-separates-from-float.html.ini

@@ -0,0 +1,2 @@
+[new-fc-separates-from-float.html]
+  expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/normal-flow/block-in-inline-hittest-float-001.html.ini

@@ -1,3 +0,0 @@
-[block-in-inline-hittest-float-001.html]
-  [block-in-inline-hittest-float-001]
-    expected: FAIL

tests/wpt/metadata-layout-2020/css/CSS2/normal-flow/block-in-inline-hittest-float-002.html.ini

@@ -1,15 +0,0 @@
-[block-in-inline-hittest-float-002.html]
-  [block-in-inline-hittest-float-002]
-    expected: FAIL
-
-  [with background]
-    expected: FAIL
-
-  [with padding]
-    expected: FAIL
-
-  [floats before block-in-inline]
-    expected: FAIL
-
-  [floats before block-in-inline with background]
-    expected: FAIL