Initial support for hide and show in import directives

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

Index: compiler/java/com/google/dart/compiler/ast/ASTVisitor.java
===================================================================
--- compiler/java/com/google/dart/compiler/ast/ASTVisitor.java	(revision 9085)
+++ compiler/java/com/google/dart/compiler/ast/ASTVisitor.java	(working copy)
@@ -193,10 +193,22 @@
     return visitStatement(node);
   }
 
+  public R visitImportCombinator(ImportCombinator node) {
+    return visitNode(node);
+  } 
+
   public R visitImportDirective(DartImportDirective node) {
     return visitDirective(node);
   }
 
+  public R visitImportHideCombinator(ImportHideCombinator node) {
+    return visitImportCombinator(node);
+  } 
+
+  public R visitImportShowCombinator(ImportShowCombinator node) {
+    return visitImportCombinator(node);
+  } 
+
   public R visitInitializer(DartInitializer node) {
     return visitNode(node);
   }
@@ -363,5 +375,5 @@
 
   public R visitRedirectConstructorInvocation(DartRedirectConstructorInvocation node) {
     return visitInvocation(node);
-  } 
+  }
 }