Accept configurations with Promise: undefined.

Fixes Karma and anything else that uses Env#configuration
as a starting point for a Jasmine config.

src/core/Env.js

@@ -175,7 +175,10 @@ getJasmineRequireObj().Env = function(j$) {
         config.hideDisabled = configuration.hideDisabled;
       }
 
-      if (configuration.hasOwnProperty('Promise')) {
+      // Don't use hasOwnProperty to check for Promise existence because Promise
+      // can be initialized to undefined, either explicitly or by using the
+      // object returned from Env#configuration. In particular, Karma does this.
+      if (configuration.Promise) {
         if (
           typeof configuration.Promise.resolve === 'function' &&
           typeof configuration.Promise.reject === 'function'