fix mapping of html files to libraries http://code.google.com/p/dart/issues/detail?id=3586

editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/internal/model/DartLibraryImpl.java

 /*
  * Copyright (c) 2012, the Dart project authors.
  * 
  * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
  * 
  * http://www.eclipse.org/legal/epl-v10.html
  * 
  * Unless required by applicable law or agreed to in writing, software distributed under the License
  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
@@ skipping 902 matching lines @@
     });
 
     // find html files for library
     if (getDartProject().exists()) { // will not look into ExternalDartProject
 
       HashMap<String, List<String>> mapping;
       try {
         mapping = getDartProject().getHtmlMapping();
 
         final String elementName = getElementName();
-        final String libraryName = new Path(elementName).lastSegment().toString();
+        final String libraryName = getCorrespondingResource().getLocation().toPortableString();
 
         Set<String> keys = mapping.keySet();
         for (String key : keys) {
           List<String> libraries = mapping.get(key);
           if (libraries.contains(libraryName) || libraries.contains(elementName)) {
             IResource htmlFile = ResourceUtil.getResource(new File(key));
             if (htmlFile != null & htmlFile.exists()) {
               children.add(new HTMLFileImpl(DartLibraryImpl.this, (IFile) htmlFile));
             }
           }
@@ skipping 233 matching lines @@
             IFileUtilities.getContents(libraryFile),
             null);
       }
     } catch (Exception exception) {
       DartCore.logInformation("Could not read and parse the file " + fileName, exception);
       // Fall through to return null.
     }
     return null;
   }
 }