dart2js send stats, includes:

pkg/compiler/lib/src/resolution/tree_elements.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 dart2js.resolution.tree_elements;
 
 import '../constants/expressions.dart';
 import '../dart_types.dart';
 import '../diagnostics/invariant.dart' show
     invariant;
@@ skipping 26 matching lines @@
   /// This includes instantiated types, types in is-checks and as-expressions
   /// and in checked mode the types of all type-annotations.
   Iterable<DartType> get requiredTypes;
 
   void forEachConstantNode(f(Node n, ConstantExpression c));
 
   /// A set of additional dependencies.  See [registerDependency] below.
   Iterable<Element> get otherDependencies;
 
   Element operator[](Node node);
+  Map<Node, DartType> get typesCache;
 
   SendStructure getSendStructure(Send send);
 
   // TODO(johnniwinther): Investigate whether [Node] could be a [Send].
   Selector getSelector(Node node);
   Selector getGetterSelectorInComplexSendSet(SendSet node);
   Selector getOperatorSelectorInComplexSendSet(SendSet node);
   DartType getType(Node node);
   TypeMask getTypeMask(Node node);
   TypeMask getGetterTypeMaskInComplexSendSet(SendSet node);
@@ skipping 68 matching lines @@
 
   /// `true` if the [analyzedElement]'s source code contains a [TryStatement].
   bool get containsTryStatement;
 }
 
 class TreeElementMapping extends TreeElements {
   final AnalyzableElement analyzedElement;
   Map<Spannable, Selector> _selectors;
   Map<Spannable, TypeMask> _typeMasks;
   Map<Node, DartType> _types;
+  Map<Node, DartType> typesCache = <Node, DartType>{};
   Setlet<Node> _superUses;
   Setlet<Element> _otherDependencies;
   Map<Node, ConstantExpression> _constants;
   Map<VariableElement, List<Node>> _potentiallyMutated;
   Map<Node, Map<VariableElement, List<Node>>> _potentiallyMutatedIn;
   Map<VariableElement, List<Node>> _potentiallyMutatedInClosure;
   Map<Node, Map<VariableElement, List<Node>>> _accessedByClosureIn;
   Setlet<Element> _elements;
   Maplet<Send, SendStructure> _sendStructureMap;
   Setlet<DartType> _requiredTypes;
@@ skipping 393 matching lines @@
   }
 
   void setCurrentTypeMask(ForIn node, TypeMask mask) {
     _setTypeMask(node.inToken, mask);
   }
 
   TypeMask getCurrentTypeMask(ForIn node) {
     return _getTypeMask(node.inToken);
   }
 }