Remove deprecated string features.

sdk/lib/io/http_impl.dart

Index: sdk/lib/io/http_impl.dart
diff --git a/sdk/lib/io/http_impl.dart b/sdk/lib/io/http_impl.dart
index 4a8d266a2fb10cbc5186ae5000db40eb0b87cb18..8f7abf1fbd54b82ca5268f0353d1f0ab7aa3a3bb 100644
--- a/sdk/lib/io/http_impl.dart
+++ b/sdk/lib/io/http_impl.dart
@@ -585,10 +585,10 @@ class _HttpResponse extends _HttpRequestResponseBase implements HttpResponse {
       _httpConnection._write(_Const.HTTP10);
     }
     _writeSP();
-    data = _statusCode.toString().charCodes;
+    data = _statusCode.toString().codeUnits;
     _httpConnection._write(data);
     _writeSP();
-    data = reasonPhrase.charCodes;
+    data = reasonPhrase.codeUnits;
     _httpConnection._write(data);
     _writeCRLF();
 
@@ -1235,7 +1235,7 @@ class _HttpClientRequest
     List<int> data;
 
     // Write request line.
-    data = _method.toString().charCodes;
+    data = _method.toString().codeUnits;
     _httpConnection._write(data);
     _writeSP();
     // Send the path for direct connections and the whole URL for
@@ -1250,9 +1250,9 @@ class _HttpClientRequest
           path = "${path}?${_uri.query}";
         }
       }
-      data = path.charCodes;
+      data = path.codeUnits;
     } else {
-      data = _uri.toString().charCodes;
+      data = _uri.toString().codeUnits;
     }
     _httpConnection._write(data);
     _writeSP();