Bug 1950035 [wpt PR 50897] - Support for the isolation CSS property, a=testonly

Automatic update from web-platform-tests
Add behavior test

Signed-off-by: Oriol Brufau <obrufauigalia.com>

--

wpt-commits: 72098edd0ca9e29d82206812df6ad96f1de76638
wpt-pr: 50897

UltraBlame original commit: b0b7f8990ba49874bf914f83eaed846394400ead

Author: marco-c

testing/web-platform/tests/css/compositing/isolation/isolation-establishes-stacking-context.html

@@ -0,0 +1,247 @@
+<
+!
+DOCTYPE
+html
+>
+<
+meta
+charset
+=
+"
+utf
+-
+8
+"
+>
+<
+title
+>
+CSS
+Compositing
+and
+Blending
+:
+The
+isolation
+property
+<
+/
+title
+>
+<
+link
+rel
+=
+"
+author
+"
+title
+=
+"
+Oriol
+Brufau
+"
+href
+=
+"
+mailto
+:
+obrufau
+igalia
+.
+com
+"
+>
+<
+link
+rel
+=
+"
+help
+"
+href
+=
+"
+https
+:
+/
+/
+www
+.
+w3
+.
+org
+/
+TR
+/
+compositing
+-
+1
+/
+#
+isolation
+"
+>
+<
+link
+rel
+=
+"
+match
+"
+href
+=
+"
+.
+.
+/
+.
+.
+/
+reference
+/
+ref
+-
+filled
+-
+green
+-
+100px
+-
+square
+.
+xht
+"
+>
+<
+meta
+name
+=
+"
+assert
+"
+content
+=
+"
+For
+CSS
+setting
+isolation
+to
+isolate
+will
+turn
+the
+element
+into
+a
+stacking
+context
+.
+"
+>
+<
+style
+>
+#
+parent
+{
+width
+:
+100px
+;
+height
+:
+100px
+;
+isolation
+:
+isolate
+;
+background
+:
+red
+;
+}
+#
+child
+{
+width
+:
+100px
+;
+height
+:
+100px
+;
+position
+:
+relative
+;
+z
+-
+index
+:
+-
+1
+;
+background
+:
+green
+;
+}
+<
+/
+style
+>
+<
+p
+>
+Test
+passes
+if
+there
+is
+a
+filled
+green
+square
+and
+<
+strong
+>
+no
+red
+<
+/
+strong
+>
+.
+<
+/
+p
+>
+<
+div
+id
+=
+"
+parent
+"
+>
+<
+div
+id
+=
+"
+child
+"
+>
+<
+/
+div
+>
+<
+/
+div
+>