initial sync*, part of #221

test/codegen/expect/syncstar_yieldstar_test.js

+dart_library.library('syncstar_yieldstar_test', null, /* Imports */[
+  "dart_runtime/dart",
+  'dart/core',
+  'expect'
+], /* Lazy imports */[
+], function(exports, dart, core, expect) {
+  'use strict';
+  let dartx = dart.dartx;
+  function* bar() {
+    let i = 1;
+    let j = 1;
+    while (true) {
+      yield i;
+      j = dart.notNull(i) + dart.notNull(j);
+      i = dart.notNull(j) - dart.notNull(i);
+    }
+  }
+  dart.fn(bar);
+  function* foo() {
+    yield* [1, 2, 3];
+    yield null;
+    yield* dart.as(bar(), core.Iterable);
+  }
+  dart.fn(foo);
+  function main() {
+    expect.Expect.listEquals([1, 2, 3, null, 1, 1, 2, 3, 5], dart.as(dart.dsend(dart.dsend(foo(), 'take', 9), 'toList'), core.List));
+  }
+  dart.fn(main);
+  // Exports:
+  exports.bar = bar;
+  exports.foo = foo;
+  exports.main = main;
+});