Index: node_modules/autoprefixer/lib/hacks/mask-composite.js
===================================================================
--- node_modules/autoprefixer/lib/hacks/mask-composite.js	(revision 2058e5c694bb6097866a5fe6503c519e8f74970f)
+++ node_modules/autoprefixer/lib/hacks/mask-composite.js	(revision 2058e5c694bb6097866a5fe6503c519e8f74970f)
@@ -0,0 +1,88 @@
+let Declaration = require('../declaration')
+
+class MaskComposite extends Declaration {
+  /**
+   * Prefix mask-composite for webkit
+   */
+  insert(decl, prefix, prefixes) {
+    let isCompositeProp = decl.prop === 'mask-composite'
+
+    let compositeValues
+
+    if (isCompositeProp) {
+      compositeValues = decl.value.split(',')
+    } else {
+      compositeValues = decl.value.match(MaskComposite.regexp) || []
+    }
+
+    compositeValues = compositeValues.map(el => el.trim()).filter(el => el)
+    let hasCompositeValues = compositeValues.length
+
+    let compositeDecl
+
+    if (hasCompositeValues) {
+      compositeDecl = this.clone(decl)
+      compositeDecl.value = compositeValues
+        .map(value => MaskComposite.oldValues[value] || value)
+        .join(', ')
+
+      if (compositeValues.includes('intersect')) {
+        compositeDecl.value += ', xor'
+      }
+
+      compositeDecl.prop = prefix + 'mask-composite'
+    }
+
+    if (isCompositeProp) {
+      if (!hasCompositeValues) {
+        return undefined
+      }
+
+      if (this.needCascade(decl)) {
+        compositeDecl.raws.before = this.calcBefore(prefixes, decl, prefix)
+      }
+
+      return decl.parent.insertBefore(decl, compositeDecl)
+    }
+
+    let cloned = this.clone(decl)
+    cloned.prop = prefix + cloned.prop
+
+    if (hasCompositeValues) {
+      cloned.value = cloned.value.replace(MaskComposite.regexp, '')
+    }
+
+    if (this.needCascade(decl)) {
+      cloned.raws.before = this.calcBefore(prefixes, decl, prefix)
+    }
+
+    decl.parent.insertBefore(decl, cloned)
+
+    if (!hasCompositeValues) {
+      return decl
+    }
+
+    if (this.needCascade(decl)) {
+      compositeDecl.raws.before = this.calcBefore(prefixes, decl, prefix)
+    }
+    return decl.parent.insertBefore(decl, compositeDecl)
+  }
+}
+
+MaskComposite.names = ['mask', 'mask-composite']
+
+MaskComposite.oldValues = {
+  add: 'source-over',
+  exclude: 'xor',
+  intersect: 'source-in',
+  subtract: 'source-out'
+}
+
+MaskComposite.regexp = new RegExp(
+  `\\s+(${Object.keys(MaskComposite.oldValues).join(
+    '|'
+  )})\\b(?!\\))\\s*(?=[,])`,
+  'ig'
+)
+
+module.exports = MaskComposite