Implement Element::has_css_layout_box()

Calling scroll() on an element which is not rendered (by a parent with
display: none) would previously cause a crash. In fact, we should
terminate the algorithm
[https://drafts.csswg.org/cssom-view/#dom-element-scroll] at step 10 in
this situation.

The fix hinges on implementing Element::has_css_layout_box() correctly,
rather than just returning true in all cases as we did previously.

Fixes #19430.
This commit is contained in:
Jon Leighton 2018-01-18 11:57:22 +01:00
parent 9f2b33c646
commit 902edb925e
3 changed files with 36 additions and 4 deletions

View file

@ -349,11 +349,12 @@ impl Element {
} }
// https://drafts.csswg.org/cssom-view/#css-layout-box // https://drafts.csswg.org/cssom-view/#css-layout-box
// Elements that have a computed value of the display property //
// that is table-column or table-column-group // We'll have no content box if there's no fragment for the node, and we use
// FIXME: Currently, it is assumed to be true always // bounding_content_box, for simplicity, to detect this (rather than making a more specific
// query to the layout thread).
fn has_css_layout_box(&self) -> bool { fn has_css_layout_box(&self) -> bool {
true self.upcast::<Node>().bounding_content_box().is_some()
} }
// https://drafts.csswg.org/cssom-view/#potentially-scrollable // https://drafts.csswg.org/cssom-view/#potentially-scrollable

View file

@ -308101,6 +308101,12 @@
{} {}
] ]
], ],
"css/cssom-view/scroll-no-layout-box.html": [
[
"/css/cssom-view/scroll-no-layout-box.html",
{}
]
],
"css/cssom-view/scrollIntoView-shadow.html": [ "css/cssom-view/scrollIntoView-shadow.html": [
[ [
"/css/cssom-view/scrollIntoView-shadow.html", "/css/cssom-view/scrollIntoView-shadow.html",
@ -516726,6 +516732,10 @@
"966ebff69f91c0ea92f4bc2f943df9ef9dc3bcf9", "966ebff69f91c0ea92f4bc2f943df9ef9dc3bcf9",
"testharness" "testharness"
], ],
"css/cssom-view/scroll-no-layout-box.html": [
"8f423a757bd716c9c22e82fd2f35007d05982c08",
"testharness"
],
"css/cssom-view/scrollIntoView-shadow.html": [ "css/cssom-view/scrollIntoView-shadow.html": [
"3c4a18992105fd7bf19cbf29f0b6d80cb12ca98c", "3c4a18992105fd7bf19cbf29f0b6d80cb12ca98c",
"testharness" "testharness"

View file

@ -0,0 +1,21 @@
<!DOCTYPE html>
<meta charset=utf-8>
<title>cssom-view - Scrolling element with no layout box</title>
<link rel="help" href="https://drafts.csswg.org/cssom-view/#dom-element-scroll">
<link rel="help" href="https://drafts.csswg.org/cssom-view/#css-layout-box">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div style="display: none">
<div id="elem"></div>
</div>
<script>
test(() => {
const elem = document.getElementById('elem');
elem.scroll(1, 2);
assert_equals(elem.scrollTop, 0, "scrollTop should be unchanged");
assert_equals(elem.scrollLeft, 0, "scrollLeft should be unchanged");
}, "scrolling an element with no CSS layout box should have no effect");
</script>