Use static dispatch for dynamic on Object methods

lib/src/compiler/code_generator.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.
 
 import 'dart:collection' show HashMap, HashSet;
 
 import 'package:analyzer/analyzer.dart' hide ConstantEvaluator;
 import 'package:analyzer/dart/ast/ast.dart' hide ConstantEvaluator;
 import 'package:analyzer/dart/ast/token.dart' show Token, TokenType;
 import 'package:analyzer/dart/element/element.dart';
@@ skipping 3121 matching lines @@
   bool _requiresStaticDispatch(Expression target, String memberName) {
     var type = getStaticType(target);
     if (!isObjectProperty(memberName)) {
       return false;
     }
 
     // If the target could be `null`, we need static dispatch.
     // If the target may be an extension type, we also use static dispatch
     // as we don't symbolize object properties like hashCode.
     return isNullable(target) ||
+        type.isDynamic ||
         (_extensionTypes.contains(type.element) && target is! SuperExpression);
   }
 
   /// Shared code for [PrefixedIdentifier] and [PropertyAccess].
   JS.Expression _emitAccess(Expression target, SimpleIdentifier memberId) {
     var member = memberId.staticElement;
     if (member is PropertyAccessorElement) {
       member = (member as PropertyAccessorElement).variable;
     }
     bool isStatic = member is ClassMemberElement && member.isStatic;
@@ skipping 708 matching lines @@
 }
 
 bool isLibraryPrefix(Expression node) =>
     node is SimpleIdentifier && node.staticElement is PrefixElement;
 
 LibraryElement _getLibrary(AnalysisContext c, String uri) =>
     c.computeLibraryElement(c.sourceFactory.forUri(uri));
 
 bool _isDartRuntime(LibraryElement l) =>
     l.isInSdk && l.source.uri.toString() == 'dart:_runtime';