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

tests/standalone/io/http_client_request_test.dart

Index: tests/standalone/io/http_client_request_test.dart
diff --git a/tests/standalone/io/http_client_request_test.dart b/tests/standalone/io/http_client_request_test.dart
index cd2a7beb045adca865c1232f7cea83fe1780d193..9015b9f4abf46eb58162ff88e6fad13952bcb6ea 100644
--- a/tests/standalone/io/http_client_request_test.dart
+++ b/tests/standalone/io/http_client_request_test.dart
@@ -108,8 +108,25 @@ void testBadResponseClose() {
 }
 
 
+void testBadHeaders() {
+  asyncStart();
+  testClientRequest((request) {
+    var value = "a";
+    for (int i = 0; i < 8 * 1024; i++) {
+      value += 'a';
+    }
+    request.headers.set('name', value);
+    request.done.catchError((error) {
+      asyncEnd();
+    }, test: (e) => e is HttpException);
+    return request.close();
+  });
+}
+
+
 void main() {
   testResponseDone();
   testBadResponseAdd();
   testBadResponseClose();
+  testBadHeaders();
 }