Add ImportElement and ExportElement

pkg/compiler/lib/src/dump_info.dart

 // Copyright (c) 2013, 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.
 
 library dump_info;
 
 import 'dart:convert'
     show HtmlEscape, JsonEncoder, StringConversionSink, ChunkedConversionSink;
 
 import 'package:dart2js_info/info.dart';
@@ skipping 64 matching lines @@
     return _elementToInfo.putIfAbsent(element, () => visit(element));
   }
 
   Info visitElement(Element element, _) => null;
 
   FunctionInfo visitConstructorBodyElement(ConstructorBodyElement e, _) {
     return visitFunctionElement(e.constructor, _);
   }
 
   LibraryInfo visitLibraryElement(LibraryElement element, _) {
-    String libname = element.getLibraryName();
-    libname = libname == "" ? "<unnamed>" : libname;
+    String libname = element.hasLibraryName ? element.libraryName : "<unnamed>";
     int size = compiler.dumpInfoTask.sizeOf(element);
     LibraryInfo info =
       new LibraryInfo(libname, element.canonicalUri, null, size);
     _elementToInfo[element] = info;
 
     LibraryElement realElement = element.isPatched ? element.patch : element;
     realElement.forEachLocalMember((Element member) {
       Info child = this.process(member);
       if (child is ClassInfo) {
         info.classes.add(child);
@@ skipping 465 matching lines @@
 
     ChunkedConversionSink<Object> sink = encoder.startChunkedConversion(
         new StringConversionSink.fromStringSink(buffer));
     sink.add(result.toJson());
     compiler.reportInfo(NO_LOCATION_SPANNABLE, MessageKind.GENERIC, {
       'text': "View the dumped .info.json file at "
           "https://dart-lang.github.io/dump-info-visualizer"
     });
   }
 }