Make the universe parts into small libraries.

pkg/compiler/lib/src/world.dart

Index: pkg/compiler/lib/src/world.dart
diff --git a/pkg/compiler/lib/src/world.dart b/pkg/compiler/lib/src/world.dart
index 6cfa45f9700bf74ff7d9ffbc36b8351f07834fe1..68dbaf20702c9ef14143f02b34342690e19e1040 100644
--- a/pkg/compiler/lib/src/world.dart
+++ b/pkg/compiler/lib/src/world.dart
@@ -27,11 +27,13 @@ import 'elements/elements.dart' show
     VariableElement;
 import 'ordered_typeset.dart';
 import 'types/types.dart' as ti;
-import 'universe/universe.dart' show
-    FunctionSet,
-    Selector,
-    SideEffects;
 import 'universe/class_set.dart';
+import 'universe/function_set.dart' show
+    FunctionSet;
+import 'universe/selector.dart' show
+    Selector;
+import 'universe/side_effects.dart' show
+    SideEffects;
 import 'util/util.dart' show
     Link;