Support the same parameter key more than once in Uri query parameters.

tests/corelib/uri_parameters_all_test.dart

+// Copyright (c) 2015, 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";
+import 'dart:convert';
+
+main() {
+  testAll(["a", "b", "c"]);
+  testAll([""]);
+  testAll(["a"]);
+  testAll(["",""]);
+  testAll(["baz"]);
+
+  testParse("z&y&w&z", {"z": ["", ""], "y": [""], "w": [""]});
+  testParse("x=42&y=42&x=37&y=37", {"x": ["42", "37"], "y": ["42", "37"]});
+  testParse("x&x&x&x&x", {"x": ["", "", "", "", ""]});
+  testParse("x=&&y", {"x": [""], "y": [""]});
+}
+
+testAll(List values) {
+  var uri = new Uri(scheme: "foo", path: "bar",
+                    queryParameters: {"baz": values});
+  var list = uri.queryParametersAll["baz"];
+  Expect.listEquals(values, list);
+}
+
+testParse(query, results) {
+  var uri = new Uri(scheme: "foo", path: "bar", query: query);
+  var params = uri.queryParametersAll;
+  for (var k in results.keys) {
+    Expect.listEquals(results[k], params[k]);
+  }
+  uri = new Uri(scheme: "foo", path: "bar", queryParameters: results);
+  params = uri.queryParametersAll;
+  for (var k in results.keys) {
+    Expect.listEquals(results[k], params[k]);
+  }
+}