Merge pull request #11300 from grpc/fengli79-patch-1

Remove the section for b64 encoded trailers.

doc/PROTOCOL-WEB.md

@@ -103,10 +103,6 @@ to security policies with XHR
   * While the server runtime will always base64-encode and flush gRPC messages
   atomically the client library should not assume base64 padding always
   happens at the boundary of message frames. That is, the implementation may send base64-encoded "chunks" with potential padding whenever the runtime needs to flush a byte buffer.
-3. For binary trailers, when the content-type is set to
-application/grpc-web-text, the extra base64 encoding specified
-in [gRPC over HTTP2](http://www.grpc.io/docs/guides/wire.html)
-for binary custom metadata is skipped.
 
 # Other features