Remove dart2jslib.dart

pkg/compiler/lib/src/dart_backend/backend_ast_to_frontend_ast.dart

Index: pkg/compiler/lib/src/dart_backend/backend_ast_to_frontend_ast.dart
diff --git a/pkg/compiler/lib/src/dart_backend/backend_ast_to_frontend_ast.dart b/pkg/compiler/lib/src/dart_backend/backend_ast_to_frontend_ast.dart
index 9f2c79f843c012613b8c4c72adef776e67e88954..f6acbe1d7b0319ab593532d527f3048e750b1ff9 100644
--- a/pkg/compiler/lib/src/dart_backend/backend_ast_to_frontend_ast.dart
+++ b/pkg/compiler/lib/src/dart_backend/backend_ast_to_frontend_ast.dart
@@ -6,7 +6,8 @@ library dart_tree_printer;
 
 import '../constants/values.dart' as values;
 import '../dart_types.dart' as types;
-import '../dart2jslib.dart' as dart2js;
+import '../diagnostics/invariant.dart' show
+    invariant;
 import '../elements/elements.dart' as elements;
 import '../resolution/resolution.dart' show
     TreeElementMapping;
@@ -1151,7 +1152,7 @@ class TreePrinter {
   tree.NamedMixinApplication makeNamedMixinApplication(
        elements.MixinApplicationElement cls) {
 
-    assert(dart2js.invariant(cls, !cls.isUnnamedMixinApplication,
+    assert(invariant(cls, !cls.isUnnamedMixinApplication,
         message: "Cannot create ClassNode for unnamed mixin application "
                  "$cls."));
     tree.Modifiers modifiers = makeModifiers(isAbstract: cls.isAbstract);
@@ -1198,7 +1199,7 @@ class TreePrinter {
 
   /// Creates a [tree.ClassNode] node for [cls].
   tree.ClassNode makeClassNode(elements.ClassElement cls) {
-    assert(dart2js.invariant(cls, !cls.isUnnamedMixinApplication,
+    assert(invariant(cls, !cls.isUnnamedMixinApplication,
         message: "Cannot create ClassNode for unnamed mixin application "
                  "$cls."));
     tree.Modifiers modifiers = makeModifiers(isAbstract: cls.isAbstract);