Fix warnings in dart2js.

dart/lib/compiler/implementation/typechecker.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 TypeCheckerTask extends CompilerTask {
   TypeCheckerTask(Compiler compiler) : super(compiler);
   String get name => "Type checker";
 
   static const bool LOG_FAILURES = false;
 
@@ skipping 906 matching lines @@
     return unhandledExpression();
   }
 
   visitCatchBlock(CatchBlock node) {
     return unhandledStatement();
   }
 
   visitTypedef(Typedef node) {
     return unhandledStatement();
   }
+
+  DartType visitNode(Node node) {
+    compiler.unimplemented('visitNode', node: node);
+  }
+
+  DartType visitCombinator(Combinator node) {
+    compiler.unimplemented('visitNode', node: node);
+  }
+
+  DartType visitExport(Export node) {
+    compiler.unimplemented('visitNode', node: node);
+  }
+
+  DartType visitExpression(Expression node) {
+    compiler.unimplemented('visitNode', node: node);
+  }
+
+  DartType visitGotoStatement(GotoStatement node) {
+    compiler.unimplemented('visitNode', node: node);
+  }
+
+  DartType visitImport(Import node) {
+    compiler.unimplemented('visitNode', node: node);
+  }
+
+  DartType visitLibraryName(LibraryName node) {
+    compiler.unimplemented('visitNode', node: node);
+  }
+
+  DartType visitLibraryTag(LibraryTag node) {
+    compiler.unimplemented('visitNode', node: node);
+  }
+
+  DartType visitLiteral(Literal node) {
+    compiler.unimplemented('visitNode', node: node);
+  }
+
+  DartType visitPart(Part node) {
+    compiler.unimplemented('visitNode', node: node);
+  }
+
+  DartType visitPartOf(PartOf node) {
+    compiler.unimplemented('visitNode', node: node);
+  }
+
+  DartType visitPostfix(Postfix node) {
+    compiler.unimplemented('visitNode', node: node);
+  }
+
+  DartType visitPrefix(Prefix node) {
+    compiler.unimplemented('visitNode', node: node);
+  }
+
+  DartType visitStatement(Statement node) {
+    compiler.unimplemented('visitNode', node: node);
+  }
+
+  DartType visitStringNode(StringNode node) {
+    compiler.unimplemented('visitNode', node: node);
+  }
 }