🎨 Support non-native promises

lib/common/api/exports/electron.js

@@ -43,6 +43,11 @@ exports.defineProperties = function (exports) {
       get: function () {
         return require('../deprecations')
       }
+    },
+    isPromise: {
+      get: function () {
+        return require('../is-promise')
+      }
     }
   })
 }

lib/common/api/is-promise.js

@@ -0,0 +1,14 @@
+'use strict'
+
+module.exports = function isPromise (val) {
+  return (
+    val &&
+    val.then &&
+    val.then instanceof Function &&
+    val.constructor &&
+    val.constructor.reject &&
+    val.constructor.reject instanceof Function &&
+    val.constructor.resolve &&
+    val.constructor.resolve instanceof Function
+  )
+}