show category information for sdk libs

editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/filesview/DartLibraryNode.java

Index: editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/filesview/DartLibraryNode.java
===================================================================
--- editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/filesview/DartLibraryNode.java	(revision 12204)
+++ editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/filesview/DartLibraryNode.java	(working copy)
@@ -32,6 +32,7 @@
   private DartDirectoryNode parent;
   private IFileStore root;
   private String name;
+  private String category;
 
   public DartLibraryNode(DartDirectoryNode parent, IFileStore root, String name) {
     this.parent = parent;
@@ -39,6 +40,17 @@
     this.name = name;
   }
 
+  public DartLibraryNode(DartDirectoryNode parent, IFileStore root, String name, String category) {
+    this.parent = parent;
+    this.root = root;
+    this.name = name;
+    this.category = category;
+  }
+
+  public String getCategory() {
+    return category;
+  }
+
   public IFileStore[] getFiles() {
     try {
       List<IFileStore> members = filteredMembers(root);