dart2js: add support for configuration-specific imports.

pkg/compiler/lib/src/tree/prettyprint.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.
 
 part of tree;
 
 /**
  * Pretty-prints Node tree in XML-like format.
  *
  * TODO(smok): Add main() to run from command-line to print out tree for given
@@ skipping 70 matching lines @@
     visitChildNode(node.superclass, "superclass");
     visitChildNode(node.interfaces, "interfaces");
     visitChildNode(node.typeParameters, "typeParameters");
     closeNode();
   }
 
   visitConditional(Conditional node) {
     visitNodeWithChildren(node, "Conditional");
   }
 
+  visitConditionalUri(ConditionalUri node) {
+    visitNodeWithChildren(node, "ConditionalUri");
+  }
+
   visitContinueStatement(ContinueStatement node) {
     visitNodeWithChildren(node, "ContinueStatement");
   }
 
+  visitDottedName(DottedName node) {
+    openNode(node, "DottedName");
+    visitChildNode(node.identifiers, "identifiers");
+    closeNode();
+  }
+
   visitDoWhile(DoWhile node) {
     visitNodeWithChildren(node, "DoWhile");
   }
 
   visitEmptyStatement(EmptyStatement node) {
     visitNodeWithChildren(node, "EmptyStatement");
   }
 
   visitEnum(Enum node) {
     visitNodeWithChildren(node, "Enum");
@@ skipping 268 matching lines @@
 
   visitCombinator(Combinator node) {
     openNode(node, "Combinator", {"isShow" : "${node.isShow}",
                                   "isHide" : "${node.isHide}"});
     closeNode();
   }
 
   visitExport(Export node) {
     openNode(node, "Export");
     visitChildNode(node.uri, "uri");
+    if (node.conditionalUris != null) {
+      visitChildNode(node.conditionalUris, "conditionalUris");
+    }
     visitChildNode(node.combinators, "combinators");
     closeNode();
   }
 
   visitImport(Import node) {
     openNode(node, "Import", {
       "isDeferred" : "${node.isDeferred}"});
     visitChildNode(node.uri, "uri");
+    if (node.conditionalUris != null) {
+      visitChildNode(node.conditionalUris, "conditionalUris");
+    }
     visitChildNode(node.combinators, "combinators");
     if (node.prefix != null) {
       visitChildNode(node.prefix, "prefix");
     }
     closeNode();
   }
 
   visitPart(Part node) {
     openNode(node, "Part");
     visitChildNode(node.uri, "uri");
@@ skipping 53 matching lines @@
   }
 
   visitGotoStatement(GotoStatement node) {
     unimplemented('visitNode', node: node);
   }
 
   unimplemented(String message, {Node node}) {
     throw message;
   }
 }