Issue 6770. Support for @deprecated on library directive.

compiler/java/com/google/dart/compiler/ast/DartDeclaration.java

Index: compiler/java/com/google/dart/compiler/ast/DartDeclaration.java
diff --git a/compiler/java/com/google/dart/compiler/ast/DartDeclaration.java b/compiler/java/com/google/dart/compiler/ast/DartDeclaration.java
index 5080bb172fef9268c22b6f5db996993ddbaa6091..35f3013d4e0c3b7875d6f4d5a7e250be6436310f 100644
--- a/compiler/java/com/google/dart/compiler/ast/DartDeclaration.java
+++ b/compiler/java/com/google/dart/compiler/ast/DartDeclaration.java
@@ -10,7 +10,8 @@ package com.google.dart.compiler.ast;
  * considered a part of the declaration, not an independent node. So the name is not visited when
  * traversing the AST.
  */
-public abstract class DartDeclaration<N extends DartExpression> extends DartNodeWithMetadata {
+public abstract class DartDeclaration<N extends DartExpression> extends DartNodeWithMetadata
+    implements HasObsoleteMetadata {
 
   private N name; // Not visited.
   private DartComment dartDoc;