Have setters use strict -> like methods

pkg/analyzer/lib/src/task/strong/checker.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.
 
 // TODO(jmesserly): this was ported from package:dev_compiler, and needs to be
 // refactored to fit into analyzer.
 library analyzer.src.task.strong.checker;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 1386 matching lines @@
           element.enclosingElement.name,
           element.name,
           subType,
           type,
           baseType
         ]);
       }
     }
     FunctionType concreteSubType = subType;
     FunctionType concreteBaseType = baseType;
-    if (element is MethodElement) {
-      if (concreteSubType.typeFormals.isNotEmpty) {
-        if (concreteBaseType.typeFormals.isEmpty) {
-          concreteSubType = rules.instantiateToBounds(concreteSubType);
-        }
+    if (concreteSubType.typeFormals.isNotEmpty) {
+      if (concreteBaseType.typeFormals.isEmpty) {
+        concreteSubType = rules.instantiateToBounds(concreteSubType);
       }
-      concreteSubType =
-          rules.typeToConcreteType(_typeProvider, concreteSubType);
-      concreteBaseType =
-          rules.typeToConcreteType(_typeProvider, concreteBaseType);
     }
+    concreteSubType =
+        rules.typeToConcreteType(_typeProvider, concreteSubType);
+    concreteBaseType =
+        rules.typeToConcreteType(_typeProvider, concreteBaseType);
+
     if (!rules.isSubtypeOf(concreteSubType, concreteBaseType)) {
       // See whether non-subtype cases fit one of our common patterns:
       //
       // Common pattern 1: Inferable return type (on getters and methods)
       //   class A {
       //     int get foo => ...;
       //     String toString() { ... }
       //   }
       //   class B extends A {
       //     get foo => e; // no type specified.
@@ skipping 48 matching lines @@
     var visited = new Set<InterfaceType>();
     do {
       visited.add(current);
       current.mixins.reversed.forEach(
           (m) => _checkIndividualOverridesFromClass(node, m, seen, true));
       _checkIndividualOverridesFromClass(node, current.superclass, seen, true);
       current = current.superclass;
     } while (!current.isObject && !visited.contains(current));
   }
 }