use ES6 polyfill for worker and tests, not in openpgp.js

package.json

@@ -71,10 +71,10 @@
     "zlibjs": "~0.3.1"
   },
   "dependencies": {
+    "asmcrypto-lite": "git+https://github.com/openpgpjs/asmcrypto-lite.git",
+    "asn1.js": "^5.0.0",
     "bn.js": "^4.11.8",
     "buffer": "^5.0.8",
-    "asn1.js": "^5.0.0",
-    "asmcrypto-lite": "git+https://github.com/openpgpjs/asmcrypto-lite.git",
     "elliptic": "git+https://github.com/openpgpjs/elliptic.git",
     "es6-promise": "^4.2.4",
     "jwk-to-pem": "^1.2.6",

src/worker/worker.js

@@ -19,6 +19,11 @@
 
 self.window = {}; // to make UMD bundles work
 
+// ES6 Promise polyfill
+if (typeof Promise === 'undefined') {
+  require('es6-promise').polyfill();
+}
+
 importScripts('openpgp.js');
 var openpgp = window.openpgp;
 

test/unittests.js

@@ -1,3 +1,8 @@
+// ES6 Promise polyfill
+if (typeof Promise === 'undefined') {
+  require('es6-promise').polyfill();
+}
+
 (typeof window !== 'undefined' ? window : global).resolves = function(val) {
   return new Promise(function(res) { res(val); });
 };