Flush InterfaceTypeImpl cached memebers when ClassElement.version is different.

pkg/analyzer/lib/src/dart/element/type.dart

Index: pkg/analyzer/lib/src/dart/element/type.dart
diff --git a/pkg/analyzer/lib/src/dart/element/type.dart b/pkg/analyzer/lib/src/dart/element/type.dart
index 22a247ab3bfa0a509ded516f0a674157829c7ce6..df190085af056ab3edface93eaaf5be38d19a1cd 100644
--- a/pkg/analyzer/lib/src/dart/element/type.dart
+++ b/pkg/analyzer/lib/src/dart/element/type.dart
@@ -1176,6 +1176,11 @@ class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
   final List<FunctionTypeAliasElement> prunedTypedefs;
 
   /**
+   * The version of [element] for which members are cached.
+   */
+  int _versionOfCachedMembers = null;
+
+  /**
    * Cached [ConstructorElement]s - members or raw elements.
    */
   List<ConstructorElement> _constructors;
@@ -1223,6 +1228,7 @@ class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
 
   @override
   List<PropertyAccessorElement> get accessors {
+    _flushCachedMembersIfStale();
     if (_accessors == null) {
       List<PropertyAccessorElement> accessors = element.accessors;
       List<PropertyAccessorElement> members =
@@ -1237,6 +1243,7 @@ class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
 
   @override
   List<ConstructorElement> get constructors {
+    _flushCachedMembersIfStale();
     if (_constructors == null) {
       List<ConstructorElement> constructors = element.constructors;
       List<ConstructorElement> members =
@@ -1331,6 +1338,7 @@ class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
 
   @override
   List<MethodElement> get methods {
+    _flushCachedMembersIfStale();
     if (_methods == null) {
       List<MethodElement> methods = element.methods;
       List<MethodElement> members = new List<MethodElement>(methods.length);
@@ -1891,6 +1899,23 @@ class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
       instantiate(argumentTypes);
 
   /**
+   * Flush cache members if the version of [element] for which members are
+   * cached and the current version of the [element].
+   */
+  void _flushCachedMembersIfStale() {
+    ClassElement element = this.element;
+    if (element is ClassElementImpl) {
+      int currentVersion = element.version;
+      if (_versionOfCachedMembers != currentVersion) {
+        _constructors = null;
+        _accessors = null;
+        _methods = null;
+      }
+      _versionOfCachedMembers = currentVersion;
+    }
+  }
+
+  /**
    * Starting from this type, search its class hierarchy for types of the form
    * Future<R>, and return a list of the resulting R's.
    */