Make some HTTP utility functions public

tests/standalone/standalone.status

Index: tests/standalone/standalone.status
diff --git a/tests/standalone/standalone.status b/tests/standalone/standalone.status
index e690afa02415fc9c971f32fe7fe90e1f57f03266..51a5ac9454e415c4cc5da6d0858cafc0f93ed49a 100644
--- a/tests/standalone/standalone.status
+++ b/tests/standalone/standalone.status
@@ -74,7 +74,7 @@ io/skipping_dart2js_compilations_test: Skip # Library dart:uri removed.
 # Dartc spots the misuse of 'part' directives in these unit tests.
 crypto/*: Skip  # dartc cannot parse dart:io unit tests.
 io/http_headers_test: Skip  # dartc cannot parse dart:io unit tests.
-io/http_date_test: Skip  # dartc cannot parse dart:io unit tests.
+io/http_cookie_date_test: Skip  # dartc cannot parse dart:io unit tests.
 io/url_encoding_test: Skip  # dartc cannot parse dart:io unit tests.
 io/http_parser_test: Skip  # dartc cannot parse dart:io unit tests.
 io/web_socket_protocol_processor_test: Skip  # dart:io unit test.
@@ -84,7 +84,7 @@ io/process_exit_negative_test: Fail  # This is a compilation-time negative test.
 
 [ $compiler == dartanalyzer ]
 io/file_constructor_test: fail
-io/http_date_test: fail
+io/http_cookie_date_test: fail
 io/http_headers_test: fail
 io/http_parser_test: fail
 io/process_exit_negative_test: fail
@@ -99,7 +99,7 @@ io/skipping_dart2js_compilations_test: fail
 
 [ $compiler == dart2analyzer ]
 io/file_constructor_test: fail
-io/http_date_test: fail
+io/http_cookie_date_test: fail
 io/http_headers_test: fail
 io/http_parser_test: fail
 io/process_exit_negative_test: fail