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

lib/compiler/implementation/compiler.dart

Index: lib/compiler/implementation/compiler.dart
===================================================================
--- lib/compiler/implementation/compiler.dart	(revision 7416)
+++ lib/compiler/implementation/compiler.dart	(working copy)
@@ -300,6 +300,7 @@
       });
     }
     native.processNativeClasses(this, universe.libraries.getValues());
+    computeSubclasses();
     enqueue(new WorkItem.toCompile(main));
     codegenProgress.reset();
     while (!worklist.isEmpty()) {
@@ -316,6 +317,29 @@
     }
   }
 
+  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);