Add implementations for Headers, Request, Response and dart:io/dart:html clients to http_base

dart/pkg/pkg.status

Index: dart/pkg/pkg.status
diff --git a/dart/pkg/pkg.status b/dart/pkg/pkg.status
index 859b757945331ef69881625dd0a6e3432c140673..b272bea57b1640de303ced1b62bd9eefb36ace80 100644
--- a/dart/pkg/pkg.status
+++ b/dart/pkg/pkg.status
@@ -306,6 +306,7 @@ http/test/io/*: Fail, OK # Uses dart:io.
 http_parser/test/web_socket_test: Fail, OK # Uses dart:io
 http_multi_server/test/http_multi_server_test: Skip # Uses dart:io
 http_server/test/*: Fail, OK # Uses dart:io.
+http_base/test/http_base_io_test: SkipByDesign # Uses dart:io.
 intl/test/date_time_format_file_even_test: Fail, OK # Uses dart:io.
 intl/test/date_time_format_file_odd_test: Fail, OK # Uses dart:io.
 intl/test/find_default_locale_standalone_test: Fail, OK # Uses dart:io.
@@ -408,6 +409,7 @@ polymer_expressions/test/globals_test: Skip
 polymer_expressions/test/bindings_test: Skip
 third_party/html5lib/test/browser/browser_test: Skip
 http/test/html/*: Skip
+http_base/test/http_base_html_test: SkipByDesign # Uses dart:html.
 
 [ $browser ]
 docgen/test/*: Skip  # Uses dart:io