Merge pull request #1516 from syranide/es5err

Preemptively error when required ES5 shim/shams are not available

src/browser/ui/React.js

@@ -88,6 +88,34 @@ if (__DEV__) {
       'Download the React DevTools for a better development experience: ' +
       'http://fb.me/react-devtools'
     );
+
+    var expectedFeatures = [
+      // shims
+      Array.isArray,
+      Array.prototype.every,
+      Array.prototype.forEach,
+      Array.prototype.indexOf,
+      Array.prototype.map,
+      Date.now,
+      Function.prototype.bind,
+      Object.keys,
+      String.prototype.split,
+
+      // shams
+      Object.create,
+      Object.freeze
+    ];
+
+    for (var i in expectedFeatures) {
+      if (!expectedFeatures[i]) {
+        console.error(
+          'One or more ES5 shim/shams expected by React are not available: ' +
+          'http://facebook.github.io/react/docs/working-with-the-browser.html' +
+          '#polyfills-needed-to-support-older-browsers'
+        );
+        break;
+      }
+    }
   }
 }