Fix stretch in latest Firefox

data/prefixes.js

@@ -583,7 +583,15 @@ f(prefixIntrinsic, browsers =>
 )
 
 f(prefixIntrinsic, { match: /x|\s#4/ }, browsers =>
-  prefix(['fill', 'fill-available', 'stretch'], {
+  prefix(['fill', 'fill-available'], {
+    props: sizeProps,
+    feature: 'intrinsic-width',
+    browsers
+  })
+)
+
+f(prefixIntrinsic, { match: /x|\s#5/ }, browsers =>
+  prefix(['stretch'], {
     props: sizeProps,
     feature: 'intrinsic-width',
     browsers

test/autoprefixer.test.ts

@@ -1047,4 +1047,14 @@ describe('hacks', () => {
     expect(result.css).toEqual(input)
     expect(result.warnings()).toHaveLength(0)
   })
+
+  it('supports latest Firefox stretch', () => {
+    let input = read('intrinsic')
+    let output = read('intrinsic.ff')
+    let result = postcss([
+      autoprefixer({ overrideBrowserslist: 'firefox 90' })
+    ]).process(input)
+    expect(result.css).toEqual(output)
+    expect(result.warnings()).toHaveLength(2)
+  })
 })

test/cases/intrinsic.ff.css

@@ -0,0 +1,47 @@
+a {
+  width: -moz-available;
+  width: stretch;
+}
+
+b {
+  height: max-content;
+}
+
+p {
+  block-size: min-content;
+  min-inline-size: -moz-fit-content;
+  min-inline-size: fit-content;
+}
+
+.outdated {
+  width: fill;
+}
+
+.old {
+  width: fill-available;
+}
+
+.ok {
+  width: calc(100% - var(--jqx-circular-progress-bar-fill-size));
+}
+
+.grid {
+  grid: min-content max-content / fit-content(500px);
+}
+
+.grid-template {
+  grid-template: min-content / fit-content(10px) max-content;
+  grid-template: max-content 1fr max-content max-content / max-content 1fr;
+}
+
+.grid-template-columns {
+  grid-template-columns: minmax(100px, min-content);
+}
+
+.grid-auto-columns {
+  grid-auto-columns: min-content max-content;
+}
+
+.ignore {
+  width: -webkit-fill-available;
+}