Make HTTP headers use a growing buffer, not a fixed-size 8K one.

tests/standalone/io/http_server_response_test.dart

Index: tests/standalone/io/http_server_response_test.dart
diff --git a/tests/standalone/io/http_server_response_test.dart b/tests/standalone/io/http_server_response_test.dart
index c3c0afb51d6326fb79d28afd0f7da37f4a23433f..a6c06aff34072797b1870cf7106bf97b8285071b 100644
--- a/tests/standalone/io/http_server_response_test.dart
+++ b/tests/standalone/io/http_server_response_test.dart
@@ -281,20 +281,6 @@ void testIgnoreRequestData() {
 }
 
 
-void testBadHeaders() {
-  testServerRequest((server, request) {
-    var value = "a";
-    for (int i = 0; i < 8 * 1024; i++) {
-      value += 'a';
-    }
-    request.response.headers.set('name', value);
-    request.response.close().catchError((error) {
-      server.close();
-    }, test: (e) => e is HttpException);
-  });
-}
-
-
 void testWriteCharCode() {
   testServerRequest((server, request) {
     // Test that default is latin-1 (only 2 bytes).
@@ -315,6 +301,5 @@ void main() {
   testBadResponseAdd();
   testBadResponseClose();
   testIgnoreRequestData();
-  testBadHeaders();
   testWriteCharCode();
 }