Start creating a MemberSet abstraction, and use it to fold getters/setters into field accesses.

lib/compiler/implementation/compiler.dart

 // Copyright (c) 2012, 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.
 
 class WorkItem {
   final Element element;
   TreeElements resolutionTree;
   Function run;
   bool allowSpeculativeOptimization = true;
   List<HTypeGuard> guards = const <HTypeGuard>[];
@@ skipping 282 matching lines @@
           cancel('main is not a function', element: main);
         }
         FunctionElement mainMethod = main;
         FunctionSignature parameters = mainMethod.computeSignature(this);
         if (parameters.parameterCount > 0) {
           cancel('main cannot have parameters', element: mainMethod);
         }
       });
     }
     native.processNativeClasses(this, universe.libraries.getValues());
+    computeSubclasses();
     enqueue(new WorkItem.toCompile(main));
     codegenProgress.reset();
     while (!worklist.isEmpty()) {
       WorkItem work = worklist.removeLast();
       withCurrentElement(work.element, () => (work.run)(this));
     }
     workListIsClosed = true;
     assert(enqueuer.checkNoEnqueuedInvokedInstanceMethods());
     enqueuer.registerFieldClosureInvocations();
     emitter.assembleProgram();
     if (!worklist.isEmpty()) {
       internalErrorOnElement(worklist.first().element,
                              "work list is not empty");
     }
   }
 
+  void addSubtypes(ClassElement cls) {
+    for (Type type in cls.allSupertypes) {
+      List<Element> subtypes = universe.subtypes.putIfAbsent(
+        type.element,
+        () => <ClassElement>[]);
+      subtypes.add(cls);
+    }
+  }
+
+  void computeSubclasses() {
+    universe.libraries.getValues().forEach((LibraryElement library) {
+      for (Link<Element> link = library.topLevelElements;
+           !link.isEmpty();
+           link = link.tail) {
+        Element element = link.head;
+        if (!element.isClass()) continue;
+        ClassElement cls = element;
+        resolveClass(cls);
+        addSubtypes(cls);
+      }
+    });
+  }
+
   TreeElements analyzeElement(Element element) {
     assert(parser !== null);
     Node tree = parser.parse(element);
     validator.validate(tree);
     TreeElements elements = resolver.resolve(element);
     checker.check(tree, elements);
     return elements;
   }
 
   TreeElements analyze(WorkItem work) {
@@ skipping 239 matching lines @@
   }
 }
 
 class SourceSpan {
   final Uri uri;
   final int begin;
   final int end;
 
   const SourceSpan(this.uri, this.begin, this.end);
 }