Fix type error in js_dart2js.dart caught by DDC.

pkg/dev_compiler/tool/input_sdk/private/js_mirrors.dart

Index: pkg/dev_compiler/tool/input_sdk/private/js_mirrors.dart
diff --git a/pkg/dev_compiler/tool/input_sdk/private/js_mirrors.dart b/pkg/dev_compiler/tool/input_sdk/private/js_mirrors.dart
index 856009661428ad901676bb45967c5ab67bbcd2e4..e1280198b95d8ce750bf569f9611d8624d94ae9f 100644
--- a/pkg/dev_compiler/tool/input_sdk/private/js_mirrors.dart
+++ b/pkg/dev_compiler/tool/input_sdk/private/js_mirrors.dart
@@ -85,7 +85,24 @@ dynamic _getMember(Symbol 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) {