Add DartType.treatAsRaw to treat List<dynamic> as List in the backend.

sdk/lib/_internal/compiler/implementation/js_backend/constant_emitter.dart

 // Copyright (c) 2012, 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.
 
 part of js_backend;
 
 class ConstantEmitter  {
   ConstantReferenceEmitter _referenceEmitter;
   ConstantInitializerEmitter _initializerEmitter;
 
@@ skipping 314 matching lines @@
     List<jsAst.Expression> valueList = <jsAst.Expression>[];
     for (int i = 0; i < values.length; i++) {
       valueList.add(_reference(values[i]));
     }
     return valueList;
   }
 
   jsAst.Expression maybeAddTypeArguments(InterfaceType type,
                                          jsAst.Expression value) {
     if (type is InterfaceType &&
-        !type.isRaw &&
+        !type.treatAsRaw &&
         backend.classNeedsRti(type.element)) {
       InterfaceType interface = type;
       RuntimeTypes rti = backend.rti;
       Iterable<String> arguments = interface.typeArguments
           .toList(growable: false)
           .map((DartType type) => rti.getTypeRepresentation(type, (_){}));
       jsAst.Expression argumentList =
           new jsAst.LiteralString('[${arguments.join(', ')}]');
       return new jsAst.Call(getHelperProperty(backend.getSetRuntimeTypeInfo()),
                             [value, argumentList]);
     }
     return value;
   }
 }