typing_status: Fold stop into main method update.

It'd already been the case for some while that calling `stop` had the
same effect as calling `update` (previously `handle_text_input`) with
a falsy recipient.  With the API changes in the previous few commits,
this becomes quite natural to make explicit in the API.

frontend_tests/node_tests/typing_status.js

@@ -58,11 +58,6 @@ run_test('basics', () => {
         typing_status.update(worker, new_recipient);
     }
 
-    function call_stop() {
-        clear_events();
-        typing_status.stop(worker);
-    }
-
     worker = {
         get_current_time: returns_time(5),
         notify_server_start: notify_server_start,
@@ -133,7 +128,7 @@ run_test('basics', () => {
     });
 
     // Call stop with nothing going on.
-    call_stop();
+    call_handler(undefined);
     assert.deepEqual(typing_status.state, {
         next_send_start_time: undefined,
         idle_timer: undefined,
@@ -163,7 +158,7 @@ run_test('basics', () => {
     assert(events.idle_callback);
 
     // Explicitly stop alice.
-    call_stop();
+    call_handler(undefined);
     assert.deepEqual(typing_status.state, {
         next_send_start_time: undefined,
         idle_timer: undefined,

static/js/typing.js

@@ -72,7 +72,7 @@ exports.initialize = function () {
     // We send a stop-typing notification immediately when compose is
     // closed/cancelled
     $(document).on('compose_canceled.zulip compose_finished.zulip', function () {
-        typing_status.stop(worker);
+        typing_status.update(worker, undefined);
     });
 };
 

static/shared/js/typing_status.js

@@ -130,12 +130,3 @@ export function update(worker, new_recipient) {
     actually_ping_server(worker, new_recipient, current_time);
     start_or_extend_idle_timer(worker);
 }
-
-export function stop(worker) {
-    // We get this if somebody closes the compose box, but
-    // it doesn't necessarily mean we had typing indicators
-    // active before this.
-    if (state.current_recipient) {
-        stop_last_notification(worker);
-    }
-}

static/shared/js/typing_status.js.flow

@@ -16,5 +16,3 @@ declare export function update(
   worker: Worker,
   new_recipient: RecipientUserIds | void,
 ): void;
-
-declare export function stop(worker: Worker): void;