Revert "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 a6c06aff34072797b1870cf7106bf97b8285071b..c3c0afb51d6326fb79d28afd0f7da37f4a23433f 100644
--- a/tests/standalone/io/http_server_response_test.dart
+++ b/tests/standalone/io/http_server_response_test.dart
@@ -281,6 +281,20 @@ 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).
@@ -301,5 +315,6 @@ void main() {
   testBadResponseAdd();
   testBadResponseClose();
   testIgnoreRequestData();
+  testBadHeaders();
   testWriteCharCode();
 }