Prototype re-compiling methods in dart2js

lib/compiler/implementation/world.dart

Index: lib/compiler/implementation/world.dart
diff --git a/lib/compiler/implementation/world.dart b/lib/compiler/implementation/world.dart
index f616c5aa4c892251aa2f5984e0c03e6980e8324a..b6b37e7c5315ebdbbcb78f585d7d56ad51ac9356 100644
--- a/lib/compiler/implementation/world.dart
+++ b/lib/compiler/implementation/world.dart
@@ -4,8 +4,10 @@
 
 class World {
   final Map<ClassElement, Set<ClassElement>> subtypes;
+  final Map<ClassElement, Set<SourceString>> setters;
 
-  World() : subtypes = new Map<ClassElement, Set<ClassElement>>();
+  World() : subtypes = new Map<ClassElement, Set<ClassElement>>(),
+            setters = new Map<ClassElement, Set<SourceString>>();
 
   void populate(Compiler compiler, Collection<LibraryElement> libraries) {
     void addSubtypes(ClassElement cls) {
@@ -69,6 +71,18 @@ class World {
     });
     return (fieldCount == 1 && nonFieldCount == 0) ? field : null;
   }
+
+  void setterUsed(Type type, SourceString member) {
+    Set<SourceString> setters =
+        setters.putIfAbsent(type.element, () => new Set<SourceString>());
+    setters.add(member);
+  }
+
+  bool isSetterUsed(Type type, SourceString member) {
+    Set<SourceString> setters = setters[type.element];
+    if (setters === null) return false;
+    return setters.contains(member);
+  }
 }
 
 /**
@@ -85,4 +99,12 @@ class MemberSet {
   }
 
   bool isEmpty() => elements.isEmpty();
+
+  String toString() {
+    StringBuffer sb = new StringBuffer();
+    sb.add("MemberSet: {");
+    elements.every((Element element) => sb.add("${element.name}, "));
+    sb.add("}");
+    return sb.toString();
+  }
 }