Migrate test block 30 + corelib portion of block 31 to Dart 2.0.

tests/corelib_2/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() {
   // This exact data is from posting a form in Chrome 26 with the one
@@ skipping 82 matching lines @@
       encoded.write(i.toRadixString(16).toUpperCase());
     }
     if (i == 32) {
       allEncoded.write("+");
     } else {
       allEncoded.write("%");
       allEncoded.write(i.toRadixString(16).toUpperCase());
     }
     unencoded.writeCharCode(i);
   }
-  encoded = encoded.toString();
-  unencoded = unencoded.toString();
-  test("a=$encoded", {"a": unencoded});
-  test("a=$encoded&b=$encoded", {"a": unencoded, "b": unencoded});
+  var encodedStr = encoded.toString();
+  var unencodedStr = unencoded.toString();
+  test("a=$encodedStr", {"a": unencodedStr});
+  test("a=$encodedStr&b=$encodedStr", {"a": unencodedStr, "b": unencodedStr});
 
   var map = new Map();
-  map[unencoded] = unencoded;
-  test("$encoded=$encoded", map);
-  test("$encoded=$allEncoded", map, "$encoded=$encoded");
-  test("$allEncoded=$encoded", map, "$encoded=$encoded");
-  test("$allEncoded=$allEncoded", map, "$encoded=$encoded");
-  map[unencoded] = null;
-  test("$encoded", map);
-  map[unencoded] = "";
-  test("$encoded", map);
+  map[unencodedStr] = unencodedStr;
+  test("$encodedStr=$encodedStr", map);
+  test("$encodedStr=$allEncoded", map, "$encodedStr=$encodedStr");
+  test("$allEncoded=$encodedStr", map, "$encodedStr=$encodedStr");
+  test("$allEncoded=$allEncoded", map, "$encodedStr=$encodedStr");
+  map[unencodedStr] = null;
+  test("$encodedStr", map);
+  map[unencodedStr] = "";
+  test("$encodedStr", map);
 }
 
 testInvalidQueryParameters() {
   test(String query, Map<String, String> parameters) {
     check(uri) {
       Expect.equals(query, uri.query);
       if (query.isEmpty) {
         Expect.equals(query, uri.toString());
       } else {
         Expect.equals("?$query", uri.toString());
@@ skipping 45 matching lines @@
   test(new Uri(queryParameters: {"a": "b", "c": "d"}).queryParameters);
 }
 
 main() {
   testInvalidArguments();
   testEncodeQueryComponent();
   testQueryParameters();
   testInvalidQueryParameters();
   testQueryParametersImmutableMap();
 }