Move dart2jslib parts into separate libraries.

pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart

Index: pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart
diff --git a/pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart b/pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart
index e9ceabb91234f680440a6c980d05f0c2498899f4..b242c98e140d4a3a58feb1fb02e2585b75769ba2 100644
--- a/pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart
+++ b/pkg/compiler/lib/src/inferrer/simple_types_inferrer.dart
@@ -12,12 +12,14 @@ import '../dart_types.dart'
 import '../elements/elements.dart';
 import '../js_backend/js_backend.dart' as js;
 import '../native/native.dart' as native;
+import '../resolution/resolution.dart' show TreeElements;
 import '../resolution/operators.dart' as op;
 import '../tree/tree.dart' as ast;
 import '../types/types.dart'
     show TypesInferrer, FlatTypeMask, TypeMask, ContainerTypeMask,
          ElementTypeMask, ValueTypeMask, TypeSystem, MinimalInferrerEngine;
 import '../util/util.dart' show Link, Spannable, Setlet;
+import '../world.dart' show ClassWorld;
 import 'inferrer_visitor.dart';
 
 // BUG(8802): There's a bug in the analyzer that makes the re-export