Make getKeys, getValues getters (keys, values).

lib/compiler/implementation/compiler.dart

Index: lib/compiler/implementation/compiler.dart
diff --git a/lib/compiler/implementation/compiler.dart b/lib/compiler/implementation/compiler.dart
index e80dbaaf4351193c931f2b83f5ce8f27e36180bd..d05f9c8aa4371314d69f98d87a43d211c27599ae 100644
--- a/lib/compiler/implementation/compiler.dart
+++ b/lib/compiler/implementation/compiler.dart
@@ -511,7 +511,7 @@ abstract class Compiler implements DiagnosticListener {
   }
 
   void processQueue(Enqueuer world, Element main) {
-    backend.processNativeClasses(world, libraries.getValues());
+    backend.processNativeClasses(world, libraries.values);
     world.addToWorkList(main);
     progress.reset();
     world.forEach((WorkItem work) {
@@ -537,8 +537,8 @@ abstract class Compiler implements DiagnosticListener {
         internalErrorOnElement(work.element, "Work list is not empty.");
       });
     }
-    var resolved = new Set.from(enqueuer.resolution.resolvedElements.getKeys());
-    for (Element e in codegenWorld.generatedCode.getKeys()) {
+    var resolved = new Set.from(enqueuer.resolution.resolvedElements.keys);
+    for (Element e in codegenWorld.generatedCode.keys) {
       resolved.remove(e);
     }
     for (Element e in new Set.from(resolved)) {