Cherry-pick ebe1ce92f75f. rdar://128066236

    Close a WebSocketTask if it completes with an error without closing properly
    https://bugs.webkit.org/show_bug.cgi?id=274003
    rdar://110487778

    Reviewed by Brady Eidson.

    If the TCP connection has an error but we have not received a close frame, then
    CFNetwork will call didCompleteWithError but won't call the completion block of
    receiveMessageWithCompletionHandler.  This is strange, but to make our interface
    with CFNetwork more robust, close the WebSocket in this case if it hasn't already
    been closed.  WebSocketTask::didClose will ignore this call if it has already
    been closed.

    Unfortunately, the API doesn't exist to make a unit test for this.  In attempting
    to make a unit test, I filed rdar://127883777 which, when resolved will allow us
    to test cases similar to this.  That radar shows that future work is still to be
    done in this area, but manual testing verifies this fixes the issue in the
    original radar of rdar://110487778

    There are 3 ways a WebSocketTask can close:
    1. receiveMessageWithCompletionHandler completion block can be called with an error
    2. URLSession:webSocketTask:didCloseWithCode:reason: can be called
    3. URLSession:task:didCompleteWithError: can be called
    It is an error for didCompleteWithError to be called before another call has closed
    the WebSocket, so this change calling didClose whether error is null or not is correct.

    * Source/WebKit/NetworkProcess/cocoa/NetworkSessionCocoa.mm:
    (-[WKNetworkSessionDelegate URLSession:task:didCompleteWithError:]):

    Canonical link: https://commits.webkit.org/278623@main

Canonical link: https://commits.webkit.org/272448.1022@safari-7618-branch