Use patching for dart:io.

tests/standalone/io/http_headers_test.dart

Index: tests/standalone/io/http_headers_test.dart
diff --git a/tests/standalone/io/http_headers_test.dart b/tests/standalone/io/http_headers_test.dart
index fe1c11f2069a3971f64e02658ba85bbf2fb652dc..feb579a6f1f078ae8c9684ed0378dcc5e433c988 100644
--- a/tests/standalone/io/http_headers_test.dart
+++ b/tests/standalone/io/http_headers_test.dart
@@ -4,15 +4,15 @@
 
 #import('dart:math');
 
-#source("../../../runtime/bin/input_stream.dart");
-#source("../../../runtime/bin/output_stream.dart");
-#source("../../../runtime/bin/chunked_stream.dart");
-#source("../../../runtime/bin/string_stream.dart");
-#source("../../../runtime/bin/stream_util.dart");
-#source("../../../runtime/bin/http.dart");
-#source("../../../runtime/bin/http_impl.dart");
-#source("../../../runtime/bin/http_parser.dart");
-#source("../../../runtime/bin/http_utils.dart");
+#source("../../../lib/io/input_stream.dart");
+#source("../../../lib/io/output_stream.dart");
+#source("../../../lib/io/chunked_stream.dart");
+#source("../../../lib/io/string_stream.dart");
+#source("../../../lib/io/stream_util.dart");
+#source("../../../lib/io/http.dart");
+#source("../../../lib/io/http_impl.dart");
+#source("../../../lib/io/http_parser.dart");
+#source("../../../lib/io/http_utils.dart");
 
 void testMultiValue() {
   _HttpHeaders headers = new _HttpHeaders();