Fix type error in js_dart2js.dart caught by DDC.

pkg/dev_compiler/tool/input_sdk/private/js_mirrors.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 dart._js_mirrors;
 
 import 'dart:mirrors';
 import 'dart:_foreign_helper' show JS;
 import 'dart:_internal' as _internal;
 
@@ skipping 67 matching lines @@
 typedef T _Lazy<T>();
 
 dynamic _getESSymbol(Symbol symbol) =>
     _internal.Symbol.getNativeSymbol(symbol as _internal.Symbol);
 
 dynamic _getMember(Symbol symbol) {
   var privateSymbol = _getESSymbol(symbol);
   if (privateSymbol != null) {
     return privateSymbol;
   }
-  return getName(symbol);
+  var name = getName(symbol);
+  // TODO(jacobr): this code is duplicated in code_generator.dart
+  switch (name) {
+    case '[]':
+      name = '_get';
+      break;
+    case '[]=':
+      name = '_set';
+      break;
+    case 'unary-':
+      name = '_negate';
+      break;
+    case 'constructor':
+    case 'prototype':
+      name = '_$name';
+      break;
+  }
+  return name;
 }
 
 String _getNameForESSymbol(member) {
   // Convert private JS symbol "Symbol(_foo)" to string "_foo".
   assert(JS('bool', 'typeof # == "symbol"', member));
   var str = member.toString();
   assert(str.startsWith('Symbol(') && str.endsWith(')'));
   return str.substring(7, str.length - 1);
 }
 
@@ skipping 511 matching lines @@
       // TODO(vsm): Recover the param name.
       var param = new JsParameterMirror._(new Symbol(''), _wrap(type), metadata);
       params[i + args.length] = param;
     }
 
     _params = new List.unmodifiable(params);
   }
 
   String toString() => "MethodMirror on '$_name'";
 }