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

sdk/lib/io/http_headers.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.io;
 
 class _HttpHeaders implements HttpHeaders {
   final Map<String, List<String>> _headers;
   final String protocolVersion;
 
@@ skipping 447 matching lines @@
          _noFoldingHeaders.indexOf(name) != -1)) {
       return false;
     }
     return true;
   }
 
   void _finalize() {
     _mutable = false;
   }
 
-  void _build(BytesBuilder builder) {
+  int _write(Uint8List buffer, int offset) {
+    void write(List<int> bytes) {
+      int len = bytes.length;
+      for (int i = 0; i < len; i++) {
+        buffer[offset + i] = bytes[i];
+      }
+      offset += len;
+    }
+
+    // Format headers.
     for (String name in _headers.keys) {
       List<String> values = _headers[name];
       bool fold = _foldHeader(name);
       var nameData = name.codeUnits;
-      builder.add(nameData);
-      builder.addByte(_CharCode.COLON);
-      builder.addByte(_CharCode.SP);
+      write(nameData);
+      buffer[offset++] = _CharCode.COLON;
+      buffer[offset++] = _CharCode.SP;
       for (int i = 0; i < values.length; i++) {
         if (i > 0) {
           if (fold) {
-            builder.addByte(_CharCode.COMMA);
-            builder.addByte(_CharCode.SP);
+            buffer[offset++] = _CharCode.COMMA;
+            buffer[offset++] = _CharCode.SP;
           } else {
-            builder.addByte(_CharCode.CR);
-            builder.addByte(_CharCode.LF);
-            builder.add(nameData);
-            builder.addByte(_CharCode.COLON);
-            builder.addByte(_CharCode.SP);
+            buffer[offset++] = _CharCode.CR;
+            buffer[offset++] = _CharCode.LF;
+            write(nameData);
+            buffer[offset++] = _CharCode.COLON;
+            buffer[offset++] = _CharCode.SP;
           }
         }
-        builder.add(values[i].codeUnits);
+        write(values[i].codeUnits);
       }
-      builder.addByte(_CharCode.CR);
-      builder.addByte(_CharCode.LF);
+      buffer[offset++] = _CharCode.CR;
+      buffer[offset++] = _CharCode.LF;
     }
+    return offset;
   }
 
   String toString() {
     StringBuffer sb = new StringBuffer();
     _headers.forEach((String name, List<String> values) {
       sb..write(name)..write(": ");
       bool fold = _foldHeader(name);
       for (int i = 0; i < values.length; i++) {
         if (i > 0) {
           if (fold) {
@@ skipping 476 matching lines @@
             (codeUnit >= 0x23 && codeUnit <= 0x2B) ||
             (codeUnit >= 0x2D && codeUnit <= 0x3A) ||
             (codeUnit >= 0x3C && codeUnit <= 0x5B) ||
             (codeUnit >= 0x5D && codeUnit <= 0x7E))) {
         throw new FormatException(
             "Invalid character in cookie value, code unit: '$codeUnit'");
       }
     }
   }
 }