Use relative URIs for core library part-of statements.

tests/standalone/io/web_socket_ping_test.dart

Index: tests/standalone/io/web_socket_ping_test.dart
diff --git a/tests/standalone/io/web_socket_ping_test.dart b/tests/standalone/io/web_socket_ping_test.dart
index 8d16c0134871511497999f4b82f9f444e56c0365..5d7339065de975df4f9f632d48c3962f44c01241 100644
--- a/tests/standalone/io/web_socket_ping_test.dart
+++ b/tests/standalone/io/web_socket_ping_test.dart
@@ -11,10 +11,11 @@ library dart.io;
 
 import "package:expect/expect.dart";
 import "dart:async";
+import "dart:convert" show BASE64;
 import "dart:io";
 import "dart:math";
 
-part "../../../sdk/lib/io/crypto.dart";
+import "hash_utils.dart";
 
 const String webSocketGUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
 
@@ -27,9 +28,9 @@ void testPing(int totalConnections) {
       response.headers.set(HttpHeaders.CONNECTION, "upgrade");
       response.headers.set(HttpHeaders.UPGRADE, "websocket");
       String key = request.headers.value("Sec-WebSocket-Key");
-      _SHA1 sha1 = new _SHA1();
+      var sha1 = new SHA1();
       sha1.add("$key$webSocketGUID".codeUnits);
-      String accept = _CryptoUtils.bytesToBase64(sha1.close());
+      String accept = BASE64.encode(sha1.close());
       response.headers.add("Sec-WebSocket-Accept", accept);
       response.headers.contentLength = 0;
       response.detachSocket().then((socket) {