Add overscroll-behavior support

data/prefixes.js

@@ -769,3 +769,13 @@ f(bidi, { match: /y x/ }, browsers =>
         browsers
     })
 );
+
+
+// overscroll-behavior selector
+const over = require('caniuse-lite/data/features/css-overscroll-behavior.js');
+f(over, { match: /a #1/ }, browsers =>
+    prefix(['overscroll-behavior'], {
+        feature: 'css-overscroll-behavior',
+        browsers
+    })
+);

lib/hacks/overscroll-behavior.js

@@ -0,0 +1,36 @@
+
+const Declaration = require('../declaration');
+
+class OverscrollBehavior extends Declaration {
+
+    static names = ['overscroll-behavior', 'scroll-chaining'];
+
+    /**
+     * Change property name for IE
+     */
+    prefixed(prop, prefix) {
+        return prefix + 'scroll-chaining';
+    }
+
+    /**
+     * Return property name by spec
+     */
+    normalize() {
+        return 'overscroll-behavior';
+    }
+
+    /**
+     * Change value for IE
+     */
+    set(decl, prefix) {
+        if (decl.value === 'auto') {
+            decl.value = 'chained';
+        } else if (decl.value === 'none' || decl.value === 'contain') {
+            decl.value = 'none';
+        }
+        return super.set(decl, prefix);
+    }
+
+}
+
+module.exports = OverscrollBehavior;

lib/prefixes.js

@@ -48,6 +48,7 @@ Declaration.hack(require('./hacks/background-size'));
 Declaration.hack(require('./hacks/grid-row-column'));
 Declaration.hack(require('./hacks/grid-rows-columns'));
 Declaration.hack(require('./hacks/grid-column-align'));
+Declaration.hack(require('./hacks/overscroll-behavior'));
 Declaration.hack(require('./hacks/grid-template-areas'));
 Declaration.hack(require('./hacks/text-emphasis-position'));
 

test/autoprefixer.test.js

@@ -59,6 +59,9 @@ const backgrounder = autoprefixer({
 const resolutioner = autoprefixer({
     browsers: ['Safari 7', 'Opera 12']
 });
+const overscroller = autoprefixer({
+    browsers: ['Edge 16']
+});
 
 function prefixer(name) {
     if (
@@ -112,6 +115,8 @@ function prefixer(name) {
         return intrinsicer;
     } else if (name === 'supports') {
         return supporter;
+    } else if (name === 'overscroll-behavior') {
+        return overscroller;
     } else {
         return compiler;
     }
@@ -415,6 +420,7 @@ describe('hacks', () => {
     it('supports cross-fade()',         () => test('cross-fade'));
     it('supports text-decoration',      () => test('text-decoration'));
     it('ignores modern direction',      () => test('animation'));
+    it('supports overscroll-behavior',  () => test('overscroll-behavior'));
 
     it('supports appearance for IE', () => {
         const instance = autoprefixer({ browsers: 'Edge 15' });

test/cases/overscroll-behavior.css

@@ -0,0 +1,15 @@
+.none {
+    overscroll-behavior: none;
+}
+
+.contain {
+    overscroll-behavior: contain;
+}
+
+.auto {
+    overscroll-behavior: auto;
+}
+
+.inherit {
+    overscroll-behavior: inherit;
+}

test/cases/overscroll-behavior.out.css

@@ -0,0 +1,19 @@
+.none {
+    -ms-scroll-chaining: none;
+        overscroll-behavior: none;
+}
+
+.contain {
+    -ms-scroll-chaining: none;
+        overscroll-behavior: contain;
+}
+
+.auto {
+    -ms-scroll-chaining: chained;
+        overscroll-behavior: auto;
+}
+
+.inherit {
+    -ms-scroll-chaining: inherit;
+        overscroll-behavior: inherit;
+}