fix PackageLibraryManager to resolve self links to right file

compiler/java/com/google/dart/compiler/PackageLibraryManager.java

Index: compiler/java/com/google/dart/compiler/PackageLibraryManager.java
===================================================================
--- compiler/java/com/google/dart/compiler/PackageLibraryManager.java	(revision 12565)
+++ compiler/java/com/google/dart/compiler/PackageLibraryManager.java	(working copy)
@@ -5,6 +5,7 @@
 package com.google.dart.compiler;
 
 import java.io.File;
+import java.io.IOException;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.ArrayList;
@@ -46,8 +47,8 @@
 
   public static final String DART_SCHEME = "dart";
   public static final String DART_SCHEME_SPEC = "dart:";
+  
 
-
   /**
    * Answer <code>true</code> if the string is a dart spec
    */
@@ -171,8 +172,13 @@
       }
       for (URI rootUri : packageRootsUri){
         URI fileUri = rootUri.resolve(relPath);
-        if (new File(fileUri).exists()){
-          return fileUri;
+        File file = new File(fileUri);
+        if (file.exists()){
+          try {
+            return file.getCanonicalFile().toURI();
+          } catch (IOException e) {
+            file.toURI();
+          }
         }
       }
       // don't return null for package scheme
@@ -254,7 +260,11 @@
         fileUri = getResolvedPackageUri(uri, rootUri);
         File file  = new File(fileUri);
         if (file.exists()){
-          return file.toURI();
+          try {
+            return file.getCanonicalFile().toURI();
+          } catch (IOException e) {
+            return file.toURI();
+          }
         }
       }
       // resolve against first package root
@@ -263,6 +273,7 @@
     }
     return uri;
   }
+
   
   /**
    * Given a uri, resolve against the list of package roots, used to find generated files