Add import/export declaration AST node boilerplate to kernel.

pkg/kernel/lib/visitor.dart

Index: pkg/kernel/lib/visitor.dart
diff --git a/pkg/kernel/lib/visitor.dart b/pkg/kernel/lib/visitor.dart
index f61d12e514ca744b2c1d801a90b41e0c8b2c6abf..2aa31fbe2f97882cea08ce149154656b665c1d20 100644
--- a/pkg/kernel/lib/visitor.dart
+++ b/pkg/kernel/lib/visitor.dart
@@ -220,7 +220,8 @@ class TreeVisitor<R>
 
   // Other tree nodes
   R visitLibrary(Library node) => defaultTreeNode(node);
-  R visitDeferredImport(DeferredImport node) => defaultTreeNode(node);
+  R visitLibraryDependency(LibraryDependency node) => defaultTreeNode(node);
+  R visitCombinator(Combinator node) => defaultTreeNode(node);
   R visitTypedef(Typedef node) => defaultTreeNode(node);
   R visitTypeParameter(TypeParameter node) => defaultTreeNode(node);
   R visitFunctionNode(FunctionNode node) => defaultTreeNode(node);