Add a reftest for this.
Differential Revision: https://phabricator.services.mozilla.com/D15856
bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1501111
gecko-commit: d1babeef937f5cd40a840082bdb1e4252b831947
gecko-integration-branch: autoland
gecko-reviewers: jrmuizel
diff --git a/css/css-masking/clip-path/clip-path-fixed-nested-ref.html b/css/css-masking/clip-path/clip-path-fixed-nested-ref.html
new file mode 100644
index 0000000..b860304
--- /dev/null
+++ b/css/css-masking/clip-path/clip-path-fixed-nested-ref.html
@@ -0,0 +1,17 @@
+<!doctype html>
+<title>CSS Test Reference</title>
+<link rel="author" href="mailto:emilio@crisal.io" title="Emilio Cobos Álvarez">
+<style>
+ body, html {
+ margin: 0;
+ padding: 0;
+ background: green;
+ }
+
+ .purple-square {
+ background: purple;
+ width: 50px;
+ height: 50px;
+ }
+</style>
+<div class="purple-square"></div>
diff --git a/css/css-masking/clip-path/clip-path-fixed-nested.html b/css/css-masking/clip-path/clip-path-fixed-nested.html
new file mode 100644
index 0000000..5090bc2
--- /dev/null
+++ b/css/css-masking/clip-path/clip-path-fixed-nested.html
@@ -0,0 +1,38 @@
+<!doctype html>
+<title>CSS Test: nested clip-path() inside the same reference frame with position: fixed</title>
+<link rel="author" href="mailto:emilio@crisal.io" title="Emilio Cobos Álvarez">
+<link rel="author" href="https://mozilla.org" title="Mozilla">
+<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1501111">
+<link rel="help" href="https://drafts.fxtf.org/css-masking/#the-clip-path">
+<link rel="match" href="clip-path-fixed-nested-ref.html">
+<style>
+ body, html {
+ margin: 0;
+ padding: 0;
+ }
+ .outer-clip {
+ height: 100vh;
+ clip-path: inset(0 0 0 0);
+ background: green;
+ }
+ .fixed {
+ position: fixed;
+ }
+ .inner-clip {
+ height: 50px;
+ width: 50px;
+ clip-path: inset(0 0 0 0);
+ }
+ .inner-clip-contents {
+ height: 100px;
+ width: 100px;
+ background: purple;
+ }
+</style>
+<div class="outer-clip">
+ <div class="fixed">
+ <div class="inner-clip">
+ <div class="inner-clip-contents"></div>
+ </div>
+ </div>
+</div>
