Add token invariant to DiagnosticReporter

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 '../common.dart';
 import '../constants/expressions.dart';
 import '../dart_types.dart';
+import '../diagnostics/source_span.dart';
 import '../elements/elements.dart';
 import '../types/types.dart' show
     TypeMask;
 import '../tree/tree.dart';
 import '../util/util.dart';
 import '../universe/selector.dart' show
     Selector;
 
 import 'secret_tree_element.dart' show
     getTreeElement,
     setTreeElement;
 import 'send_structure.dart';
 
 abstract class TreeElements {
   AnalyzableElement get analyzedElement;
-  Iterable<Node> get superUses;
+  Iterable<SourceSpan> get superUses;
 
   void forEachConstantNode(f(Node n, ConstantExpression c));
 
   Element operator[](Node node);
   Map<Node, DartType> get typesCache;
 
   /// Returns the [SendStructure] that describes the semantics of [node].
   SendStructure getSendStructure(Send node);
 
   /// Returns the [NewStructure] that describes the semantics of [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<SourceSpan> _superUses;
   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;
   Maplet<Send, SendStructure> _sendStructureMap;
   Maplet<NewExpression, NewStructure> _newStructureMap;
   bool containsTryStatement = false;
 
   /// Map from nodes to the targets they define.
@@ skipping 59 matching lines @@
 
   void setType(Node node, DartType type) {
     if (_types == null) {
       _types = new Maplet<Node, DartType>();
     }
     _types[node] = type;
   }
 
   DartType getType(Node node) => _types != null ? _types[node] : null;
 
-  Iterable<Node> get superUses {
-    return _superUses != null ? _superUses : const <Node>[];
+  Iterable<SourceSpan> get superUses {
+    return _superUses != null ? _superUses : const <SourceSpan>[];
   }
 
-  void addSuperUse(Node node) {
+  void addSuperUse(SourceSpan span) {
     if (_superUses == null) {
-      _superUses = new Setlet<Node>();
+      _superUses = new Setlet<SourceSpan>();
     }
-    _superUses.add(node);
+    _superUses.add(span);
   }
 
   Selector _getSelector(Spannable node) {
     return _selectors != null ? _selectors[node] : null;
   }
 
   void _setSelector(Spannable node, Selector selector) {
     if (_selectors == null) {
       _selectors = new Maplet<Spannable, Selector>();
     }
@@ skipping 253 matching lines @@
   }
 
   void setCurrentTypeMask(ForIn node, TypeMask mask) {
     _setTypeMask(node.inToken, mask);
   }
 
   TypeMask getCurrentTypeMask(ForIn node) {
     return _getTypeMask(node.inToken);
   }
 }