add traceur test suite

test/fixtures/traceur/AsyncFunctions/AsyncMethod.js

@@ -0,0 +1,31 @@
+// Options: --async-functions
+// Async.
+
+function asyncTimeout(ms) {
+  return new Promise((resolve) => {
+    setTimeout(resolve, ms);
+  });
+}
+
+class C {
+  async test() {
+    var x = 0;
+    await asyncTimeout(1);
+    assert.equal(1, ++x);
+    await asyncTimeout(1);
+    assert.equal(2, ++x);
+    C.test();
+  }
+
+  static async test() {
+    var x = 0;
+    await asyncTimeout(1);
+    assert.equal(1, ++x);
+    await asyncTimeout(1);
+    assert.equal(2, ++x);
+
+    done();
+  }
+}
+
+new C().test();