Remove unparse_validator.

lib/compiler/implementation/dart_backend/backend.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 class DartBackend extends Backend {
   final List<CompilerTask> tasks;
-  final UnparseValidator unparseValidator;
 
   Map<Element, TreeElements> get resolvedElements() =>
       compiler.enqueuer.resolution.resolvedElements;
 
   DartBackend(Compiler compiler, [bool validateUnparse = false])
       : tasks = <CompilerTask>[],
-      unparseValidator = new UnparseValidator(compiler, validateUnparse),
-      super(compiler) {
-    tasks.add(unparseValidator);
-  }
+      super(compiler);
 
-  void enqueueHelpers(Enqueuer world) {
-    // TODO(antonm): Implement this method, if needed.
-  }
-
+  void enqueueHelpers(Enqueuer world) { }
   void codegen(WorkItem work) { }
-
   void processNativeClasses(Enqueuer world,
-                            Collection<LibraryElement> libraries) {
-  }
+                            Collection<LibraryElement> libraries) { }
 
   void assembleProgram() {
-    resolvedElements.forEach((element, treeElements) {
-      unparseValidator.check(element);
-    });
-
     /**
      * Tells whether we should output given element. Corelib classes like
      * Object should not be in the resulting code.
      */
     final LIBS_TO_IGNORE = [
       compiler.jsHelperLibrary,
       compiler.interceptorsLibrary,
     ];
     bool shouldOutput(Element element) =>
       element.kind !== ElementKind.VOID &&
@@ skipping 141 matching lines @@
     if (typeElement.isClass()) newClassElementCallback(typeElement);
     typeAnnotation.visitChildren(this);
   }
 
   void collect() {
     compiler.withCurrentElement(rootElement, () {
       rootElement.parseNode(compiler).accept(this);
     });
   }
 }