Use default params when --destructure-named-params + fix renaming of reserved destructured params

test/codegen/destructuring.dart

Index: test/codegen/destructuring.dart
diff --git a/test/codegen/destructuring.dart b/test/codegen/destructuring.dart
new file mode 100644
index 0000000000000000000000000000000000000000..a0912437ed357d714d59eaf3e44dedda0ccb4567
--- /dev/null
+++ b/test/codegen/destructuring.dart
@@ -0,0 +1,20 @@
+f(int a, b, [c = 1]) {
+  f(a, b, c);
+}
+g(int a, b, {c : 1}) {
+  f(a, b, c);
+}
+
+invalid_names1(int let, function, arguments) {
+  f(let, function, arguments);
+}
+invalid_names2([int let, function = 1, arguments]) {
+  f(let, function, arguments);
+}
+invalid_names3({int let, function, arguments : 2}) {
+  f(let, function, arguments);
+}
+
+names_clashing_with_object_props({int constructor, valueOf, hasOwnProperty : 2}) {
+  f(constructor, valueOf, hasOwnProperty);
+}