Avoid parsing path and query string more than once

tests/corelib/uri_query_test.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.
 
 import "package:expect/expect.dart";
 
 void testInvalidArguments() {
 }
 
 void testEncodeQueryComponent() {
@@ skipping 53 matching lines @@
     } else if (unreserved.indexOf(new String.fromCharCode(i)) != -1) {
       encoded.writeCharCode(i);
     } else {
       encoded.write("%");
       encoded.write(i.toRadixString(16).toUpperCase());
     }
     unencoded.writeCharCode(i);
   }
   encoded = encoded.toString();
   unencoded = unencoded.toString();
-  print(encoded);
-  print(unencoded);
   test("a=$encoded", {"a": unencoded});
   test("a=$encoded&b=$encoded", {"a": unencoded, "b": unencoded});
 
   var map = new Map();
   map[unencoded] = unencoded;
   test("$encoded=$encoded", map);
 }
 
 testInvalidQueryParameters() {
   test(String query, Map<String, String> parameters) {
@@ skipping 20 matching lines @@
   test("=", {});
   test("=xxx", {});
   test("===", {});
   test("=xxx=yyy=zzz", {});
   test("=&=&=", {});
   test("=xxx&=yyy&=zzz", {});
   test("&=&=&", {});
   test("&=xxx&=xxx&", {});
 }
 
+testQueryParametersImmutableMap() {
+  test(map) {
+    bool isUnsupported(e) => e is UnsupportedError;
+
+    Expect.isTrue(map.containsValue("b"));
+    Expect.isTrue(map.containsKey("a"));
+    Expect.equals("b", map["a"]);
+    Expect.throws(() => map["a"] = "c", isUnsupported);
+    Expect.throws(() => map.putIfAbsent("b", () => "e"), isUnsupported);
+    Expect.throws(() => map.remove("a"), isUnsupported);
+    Expect.throws(() => map.clear(), isUnsupported);
+    var count = 0;
+    map.forEach((key, value) => count++);
+    Expect.equals(2, count);
+    Expect.equals(2, map.keys.length);
+    Expect.equals(2, map.values.length);
+    Expect.equals(2, map.length);
+    Expect.isFalse(map.isEmpty);
+    Expect.isTrue(map.isNotEmpty);
+  }
+
+  test(Uri.parse("?a=b&c=d").queryParameters);
+  test(new Uri(queryParameters: {"a": "b", "c": "d"}).queryParameters);
+}
+
 main() {
   testInvalidArguments();
   testEncodeQueryComponent();
   testQueryParameters();
   testInvalidQueryParameters();
+  testQueryParametersImmutableMap();
 }