dart2js cps: Remove dart2dart from cps pipeline and clean up.

pkg/compiler/lib/src/use_unused_api.dart

Index: pkg/compiler/lib/src/use_unused_api.dart
diff --git a/pkg/compiler/lib/src/use_unused_api.dart b/pkg/compiler/lib/src/use_unused_api.dart
index dd46337100783e70bc3c8ece0334029c79600347..820ad9baaa1f827d2dde6fb4a9f7a0f68fe8776e 100644
--- a/pkg/compiler/lib/src/use_unused_api.dart
+++ b/pkg/compiler/lib/src/use_unused_api.dart
@@ -301,17 +301,12 @@ useSemanticVisitor() {
   new semantic_visitor.BulkDeclarationVisitor().apply(null, null);
 }
 
-class DummyTreeVisitor extends tree_ir.RootVisitor
-                          with tree_ir.InitializerVisitor {
-  visitFunctionDefinition(tree_ir.FunctionDefinition node) {}
-  visitConstructorDefinition(tree_ir.ConstructorDefinition node) {}
-  visitFieldDefinition(tree_ir.FieldDefinition node) {}
-
-  visitFieldInitializer(tree_ir.FieldInitializer node) {}
-  visitSuperInitializer(tree_ir.SuperInitializer node) {}
+class TreeVisitor1 extends tree_ir.ExpressionVisitor1
+                      with tree_ir.StatementVisitor1 {
+  noSuchMethod(inv) {}
 }
 
 useTreeVisitors() {
-  new DummyTreeVisitor().visitRootNode(null);
-  new DummyTreeVisitor().visitInitializer(null);
+  new TreeVisitor1().visitExpression(null, null);
+  new TreeVisitor1().visitStatement(null, null);
 }