fixes #145, optional params+initializing formals+private fields

lib/src/codegen/js_codegen.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dev_compiler.src.codegen.js_codegen;
 
 import 'dart:collection' show HashSet, HashMap;
 
 import 'package:analyzer/analyzer.dart' hide ConstantEvaluator;
 import 'package:analyzer/src/generated/ast.dart' hide ConstantEvaluator;
@@ skipping 867 matching lines @@
     return parameters.parameters.any((p) => p.kind != ParameterKind.REQUIRED);
   }
 
   JS.Statement _emitArgumentInitializers(FormalParameterList parameters) {
     if (parameters == null || !_hasArgumentInitializers(parameters)) {
       return null;
     }
 
     var body = [];
     for (var param in parameters.parameters) {
-      // TODO(justinfagnani): rename identifier if necessary
-      var name = param.identifier.name;
+      var jsParam = _visit(param.identifier);
 
       if (param.kind == ParameterKind.NAMED) {
+        // Parameters will be passed using their real names, not the (possibly
+        // renamed) local variable.
+        var paramName = js.string(param.identifier.name, "'");
         body.add(js.statement('let # = # && # in # ? #.# : #;', [
-          name,
+          jsParam,
           _namedArgTemp,
-          js.string(name, "'"),
+          paramName,
           _namedArgTemp,
           _namedArgTemp,
-          name,
+          paramName,
           _defaultParamValue(param),
         ]));
       } else if (param.kind == ParameterKind.POSITIONAL) {
         body.add(js.statement('if (# === void 0) # = #;', [
-          name,
-          name,
+          jsParam,
+          jsParam,
           _defaultParamValue(param)
         ]));
       }
     }
     return _statement(body);
   }
 
   JS.Expression _defaultParamValue(FormalParameter param) {
     if (param is DefaultFormalParameter && param.defaultValue != null) {
       return _visit(param.defaultValue);
@@ skipping 1469 matching lines @@
   return filepath;
 }
 
 // TODO(jmesserly): validate the library. See issue #135.
 bool _isJsNameAnnotation(DartObjectImpl value) => value.type.name == 'JsName';
 
 // TODO(jacobr): we would like to do something like the following
 // but we don't have summary support yet.
 // bool _supportJsExtensionMethod(AnnotatedNode node) =>
 //    _getAnnotation(node, "SupportJsExtensionMethod") != null;