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 7442)
+++ lib/compiler/implementation/compiler.dart	(working copy)
@@ -33,6 +33,7 @@
 class Compiler implements DiagnosticListener {
   Queue<WorkItem> worklist;
   Universe universe;
+  World world;
   String assembledCode;
   Namer namer;
   Types types;
@@ -100,6 +101,7 @@
 
   Compiler([this.tracer = const Tracer()])
       : universe = new Universe(),
+        world = new World(),
         worklist = new Queue<WorkItem>(),
         codegenProgress = new Stopwatch.start() {
     namer = new Namer(this);
@@ -299,7 +301,9 @@
         }
       });
     }
-    native.processNativeClasses(this, universe.libraries.getValues());
+    Collection<LibraryElement> libraries = universe.libraries.getValues();
+    native.processNativeClasses(this, libraries);
+    world.populate(this, libraries);
     enqueue(new WorkItem.toCompile(main));
     codegenProgress.reset();
     while (!worklist.isEmpty()) {