don't shadow default parameter scope iife and instead just apply the this and arguments - fixes #1128

test/core/fixtures/transformation/es6.parameters.default/iife-1128/exec.js

@@ -0,0 +1,9 @@
+const bar = true;
+
+function foo(a = bar, ...b) {
+  const bar = false;
+  assert.equal(b[0], 2);
+  assert.equal(b[1], 3);
+}
+
+foo(1, 2, 3);