dart:mirrors workaround for generic methods

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 63 matching lines @@
 }
 
 dynamic _defaultConstructorType(type) {
   return JS('', '#.definiteFunctionType(#, [])', _dart, type);
 }
 
 dynamic _getMixins(type) {
   return JS('', '#.getMixins(#, [])', _dart, type);
 }
 
+dynamic _getFunctionType(type) {
+  return JS('', '#.getFunctionTypeMirror(#)', _dart, type);
+}
+
 typedef T _Lazy<T>();
 
 dynamic _getESSymbol(Symbol symbol) =>
     _internal.PrivateSymbol.getNativeSymbol(symbol);
 
 dynamic _getMember(Symbol symbol) {
   var privateSymbol = _getESSymbol(symbol);
   if (privateSymbol != null) {
     return privateSymbol;
   }
@@ skipping 526 matching lines @@
       // Record metadata
       _metadata = new List<InstanceMirror>.unmodifiable(
           ftype.skip(1).map((a) => reflect(a)));
       ftype = ftype[0];
     } else {
       _metadata = const [];
     }
 
     // TODO(vsm): Handle generic function types properly.  Or deprecate mirrors
     // before we need to!
-    if (JS('bool', 'typeof(#) == "function"', ftype)) {
-      // Instantiate the generic version.
-      // TODO(vsm): Can't use arguments.length on arrow function.
-      ftype = JS('', '#.apply(null, #)', ftype, [dynamic, dynamic, dynamic]);
-    }
+    ftype = _getFunctionType(ftype);
 
     // TODO(vsm): Add named args.
     List args = ftype.args;
     List opts = ftype.optionals;
     var params = new List<ParameterMirror>(args.length + opts.length);
 
     for (var i = 0; i < args.length; ++i) {
       var type = args[i];
       var metadata = ftype.metadata[i];
       // TODO(vsm): Recover the param name.
       var param =
           new JsParameterMirror._(new Symbol(''), _wrap(type), metadata);
       params[i] = param;
     }
 
     for (var i = 0; i < opts.length; ++i) {
       var type = opts[i];
       var metadata = ftype.metadata[args.length + i];
       // 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'";
 }