Make nsPresContext's overflow propagation match the spec.

emilio · moz-wptsync-bot · commit f49b5f7a87bd · 2019-10-16T09:38:00.000+01:00
From https://drafts.csswg.org/css-overflow/#overflow-propagation: > UAs must apply the overflow-* values set on the root element to the viewport. > However, when the root element is an [HTML] html element (including XML syntax > for HTML) whose overflow value is visible (in both axes), and that element has > a body element as a child, user agents must instead apply the overflow-* > values of the first such child element to the viewport. The element from which > the value is propagated must then have a used overflow value of visible. This was out of sync with Document::IsScrollingElement, which implements the right thing. Differential Revision: https://phabricator.services.mozilla.com/D49196 bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1586600 gecko-commit: a1dfda2720234ceff5e27a8a9548201aec1e2c94 gecko-integration-branch: autoland gecko-reviewers: hiro
diff --git a/css/css-overflow/overflow-body-propagation-005.html b/css/css-overflow/overflow-body-propagation-005.html
@@ -0,0 +1,17 @@
+<!doctype html>
+<title>CSS Overflow Test: overscroll-behavior doesn't stop overflow from being propagated from the body</title>
+<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
+<link rel="author" title="Mozilla" href="https://mozilla.org">
+<link rel="help" href="https://drafts.csswg.org/css-overflow/#overflow-propagation">
+<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1586600">
+<link rel="match" href="reference/overflow-body-propagation-ref.html">
+<style>
+  :root {
+    overscroll-behavior-y: contain;
+  }
+  body {
+    overflow: scroll;
+    margin-top: 100px;
+  }
+</style>
+<body>The viewport should have scrollbars, not the body.</body>
diff --git a/css/css-overflow/overflow-body-propagation-006.html b/css/css-overflow/overflow-body-propagation-006.html
@@ -0,0 +1,17 @@
+<!doctype html>
+<title>CSS Overflow Test: scroll-snap-type doesn't stop overflow from being propagated from the body</title>
+<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
+<link rel="author" title="Mozilla" href="https://mozilla.org">
+<link rel="help" href="https://drafts.csswg.org/css-overflow/#overflow-propagation">
+<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1586600">
+<link rel="match" href="reference/overflow-body-propagation-ref.html">
+<style>
+  :root {
+    scroll-snap-type: both mandatory;
+  }
+  body {
+    overflow: scroll;
+    margin-top: 100px;
+  }
+</style>
+<body>The viewport should have scrollbars, not the body.</body>
