Fix yield * of falsy values (#711)

Author: nicolo-ribaudo

packages/runtime/runtime.js

@@ -487,7 +487,7 @@ var runtime = (function (exports) {
   };
 
   function values(iterable) {
-    if (iterable || iterable === "") {
+    if (iterable != null) {
       var iteratorMethod = iterable[iteratorSymbol];
       if (iteratorMethod) {
         return iteratorMethod.call(iterable);

test/tests.es6.js

@@ -1537,6 +1537,17 @@ describe("delegated yield", function() {
       it.next();
     }, TypeError);
   });
+
+  it("should work with falsy values", function () {
+    try {
+      Boolean.prototype[Symbol.iterator] = function* () { yield "Hello" };
+      function* gen() { yield* false; };
+
+      check(gen(), ["Hello"]);
+    } finally {
+      delete Boolean.prototype[Symbol.iterator];
+    }
+  });
 });
 
 (fullCompatibility