Fix type error in js_dart2js.dart caught by DDC.

pkg/dev_compiler/lib/js/es6/dart_sdk.js

Index: pkg/dev_compiler/lib/js/es6/dart_sdk.js
diff --git a/pkg/dev_compiler/lib/js/es6/dart_sdk.js b/pkg/dev_compiler/lib/js/es6/dart_sdk.js
index e6f62c3807cc3321ca2cee60cac91b8a876ef66f..b9c5e206d9c702938546edbd37b4d031e752edd4 100644
--- a/pkg/dev_compiler/lib/js/es6/dart_sdk.js
+++ b/pkg/dev_compiler/lib/js/es6/dart_sdk.js
@@ -13512,7 +13512,31 @@ _js_mirrors._getMember = function(symbol) {
   if (privateSymbol != null) {
     return privateSymbol;
   }
-  return _js_mirrors.getName(symbol);
+  let name = _js_mirrors.getName(symbol);
+  switch (name) {
+    case '[]':
+    {
+      name = '_get';
+      break;
+    }
+    case '[]=':
+    {
+      name = '_set';
+      break;
+    }
+    case 'unary-':
+    {
+      name = '_negate';
+      break;
+    }
+    case 'constructor':
+    case 'prototype':
+    {
+      name = dart.str`_${name}`;
+      break;
+    }
+  }
+  return name;
 };
 dart.lazyFn(_js_mirrors._getMember, () => SymbolTodynamic());
 _js_mirrors._getNameForESSymbol = function(member) {