refactor: Call stream_data.initialize() more directly.

This function used to be called initialize_from_page_params(),
and we called it indirectly through `subs.js`.

Now we call it directly from `ui_init.js`, which gives us a
bit more control over how things are initialized.  In fact,
this sets us up for the next commit, where I fix a recent
regression I introduced.

frontend_tests/node_tests/stream_data.js

@@ -631,7 +631,7 @@ run_test('create_sub', () => {
     assert.equal(antarctica_sub.color, '#76ce90');
 });
 
-run_test('initialize_from_page_params', () => {
+run_test('initialize', () => {
     function initialize() {
         page_params.subscriptions = [{
             name: 'subscriptions',
@@ -651,7 +651,7 @@ run_test('initialize_from_page_params', () => {
 
     initialize();
     page_params.realm_notifications_stream_id = -1;
-    stream_data.initialize_from_page_params();
+    stream_data.initialize();
 
     const stream_names = stream_data.get_streams_for_admin().map(elem => elem.name);
     assert(stream_names.indexOf('subscriptions') !== -1);
@@ -665,7 +665,7 @@ run_test('initialize_from_page_params', () => {
     // Simulate a private stream the user isn't subscribed to
     initialize();
     page_params.realm_notifications_stream_id = 89;
-    stream_data.initialize_from_page_params();
+    stream_data.initialize();
     assert.equal(page_params.notifications_stream, "");
 
     // Now actually subscribe the user to the stream
@@ -676,7 +676,7 @@ run_test('initialize_from_page_params', () => {
     };
 
     stream_data.add_sub('foo', foo);
-    stream_data.initialize_from_page_params();
+    stream_data.initialize();
     assert.equal(page_params.notifications_stream, "foo");
 });
 

static/js/stream_data.js

@@ -565,7 +565,7 @@ exports.get_streams_for_admin = function () {
     return subs;
 };
 
-exports.initialize_from_page_params = function () {
+exports.initialize = function () {
     color_data.claim_colors(page_params.subscriptions);
 
     function populate_subscriptions(subs, subscribed, previously_subscribed) {

static/js/subs.js

@@ -770,7 +770,6 @@ exports.sub_or_unsub = function (sub) {
 
 
 exports.initialize = function () {
-    stream_data.initialize_from_page_params();
     stream_list.create_initial_sidebar_rows();
 
     // We build the stream_list now.  It may get re-built again very shortly

static/js/ui_init.js

@@ -283,6 +283,7 @@ $(function () {
     echo.initialize();
     stream_color.initialize();
     stream_edit.initialize();
+    stream_data.initialize();
     subs.initialize();
     condense.initialize();
     lightbox.initialize();