Prepare the HTTP library for inclusion in the standalone VM (step 2)

runtime/bin/buffer_list.dart

Index: runtime/bin/buffer_list.dart
diff --git a/runtime/bin/buffer_list.dart b/runtime/bin/buffer_list.dart
index fc63dec1e9163ea0f396ffb17e1043745c7bf0b8..a6ec59010ff1fd40114581e88de33bd8066e71f8 100644
--- a/runtime/bin/buffer_list.dart
+++ b/runtime/bin/buffer_list.dart
@@ -74,6 +74,10 @@ class _BufferList {
         result = _buffers.first().getRange(_index, count);
         _index += count;
         _length -= count;
+        if (_index == _buffers.first().length) {
+          _buffers.removeFirst();
+          _index = 0;
+        }
         return result;
       } else {
         result = new ByteArray(count);