LibCore+LibTLS: Don't keep a "ready to write" notifier on all Sockets

The "ready to write" notifier we set up in generic socket connection is
really only meant to detect a successful connection. Once we have a TCP
connection, for example, it will fire on every event loop iteration.

This was causing IRC Client to max out the CPU by getting this no-op
notifier callback over and over.

Since this was only used by TLSv12, I changed that code to create its
own notifier instead. It might be possible to improve TLS performance
by only processing writes when actually needed, but I didn't look very
closely at that for this patch. :^)

Libraries/LibCore/Socket.cpp

@@ -127,11 +127,13 @@ bool Socket::common_connect(const struct sockaddr* addr, socklen_t addrlen)
         if (!m_connected) {
             m_connected = true;
             ensure_read_notifier();
+            if (m_notifier) {
+                m_notifier->remove_from_parent();
+                m_notifier = nullptr;
+            }
             if (on_connected)
                 on_connected();
         }
-        if (on_ready_to_write)
-            on_ready_to_write();
     };
     int rc = ::connect(fd(), addr, addrlen);
     if (rc < 0) {

Libraries/LibCore/Socket.h

@@ -63,7 +63,6 @@ public:
 
     Function<void()> on_connected;
     Function<void()> on_ready_to_read;
-    Function<void()> on_ready_to_write;
 
 protected:
     Socket(Type, Object* parent);