fix #29544, mixins to a class with named constructors

pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/rtti.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.
 
 /// This library defines the association between runtime objects and
 /// runtime types.
 part of dart._runtime;
 
 /// Runtime type information.  This module defines the mapping from
 /// runtime objects to their runtime type information.  See the types
@@ skipping 54 matching lines @@
   return closure;
 }
 
 lazyFn(closure, computeType) {
   tagLazy(closure, computeType);
   return closure;
 }
 
 // TODO(vsm): How should we encode the runtime type?
 final _runtimeType = JS('', 'Symbol("_runtimeType")');
-final isNamedConstructor = JS('', 'Symbol("isNamedConstructor")');
 
 final _moduleName = JS('', 'Symbol("_moduleName")');
 
 _checkPrimitiveType(obj) {
   // TODO(jmesserly): JS is used to prevent type literal wrapping.  Is there a
   // better way we can handle this?  (sra: It is super dodgy that the values
   // passed to JS are different to the values passed to a regular function - the
   // semantics are not longer that of calling an interpreter. dart2js has other
   // special functions, we could do the same.)
 
@@ skipping 95 matching lines @@
   }
   var ret = JS('', 'new #(null, #)', LazyJSType, name);
   JS('', '#.set(#, #)', _lazyJSTypes, name, ret);
   return ret;
 }
 
 /// Given a WrappedType, return the internal runtime type object.
 unwrapType(WrappedType obj) => obj._wrappedType;
 
 _getRuntimeType(value) => JS('', '#[#]', value, _runtimeType);
-getIsNamedConstructor(value) => JS('', '#[#]', value, isNamedConstructor);
 
 /// Return the module name for a raw library object.
 getModuleName(value) => JS('', '#[#]', value, _moduleName);
 
 /// Tag the runtime type of [value] to be type [t].
 void tag(value, t) {
   JS('', '#[#] = #', value, _runtimeType, t);
 }
 
 void tagComputed(value, compute) {
@@ skipping 22 matching lines @@
   if (module == null) return null;
   JS('', '#[#] = #', module, _moduleName, name);
   return module;
 }
 
 /// Track all libraries
 void trackLibraries(String moduleName, libraries, sourceMap) {
   JS('', '#.set(#, #)', _loadedSourceMaps, moduleName, sourceMap);
   JS('', '#.set(#, #)', _loadedModules, moduleName, libraries);
 }