Allow CryptoKey to be recognized even when provided by minified applications

Author: rapropos

.gitignore

@@ -1 +1,3 @@
 coverage/
+node_modules
+.idea

lib/jose-utils.js

@@ -367,5 +367,15 @@ Utils.sha256 = function(str) {
 Utils.isCryptoKey = function(rsa_key) {
   // Some browsers don't expose the CryptoKey as an object, so we need to check
   // the constructor's name.
-  return rsa_key.constructor.name == 'CryptoKey';
+  if (rsa_key.constructor.name == 'CryptoKey') {
+    return true;
+  }
+
+  // In the presence of minifiers, relying on class names can be problematic,
+  // so let's also allow objects that have an 'algorithm' property.
+  if (rsa_key.hasOwnProperty('algorithm')) {
+    return true;
+  }
+
+  return false;
 };