ThreadableWebSocketChannelClientWrapper don't need suspend / resume code.

As the WebSocket class handles suspend / resume, we can remove the suspend /
resume code from ThreadableWebSocketChannelClientWrapper.

BUG=384238
R=tyoshino

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=176303

Review URL: https://codereview.chromium.org/333223002

git-svn-id: svn://svn.chromium.org/blink/trunk@176401 bbb929c8-8fbe-4397-9dbb-9b2b20218538