add traceur test suite

test/fixtures/traceur/Scope/Error_ForInWithInitializerVar.js

@@ -0,0 +1,10 @@
+// Options: --block-binding
+// Error: :7:22: Unexpected token in
+
+var x = 0;
+
+// ES6 does not allow this.
+for (var i = (x = 1) in {}) {
+}
+
+assert.equal(1, x);