Revert "Fix loading _dynamicTabHeaderEndpoints in time under Polymer 2"

This reverts commit 027aaa76fe.

Reason for revert: underlying issue was fixed in
I529812c45edecf584897a4168fde28835feb316e,
this is causing duplicated `showchange` event fired for plugins

Bug: Issue 11336
Change-Id: I4ba5c70590ed0d9e53a95a89f0ae93378ae76364

polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js

@@ -304,7 +304,6 @@
       '_labelsChanged(_change.labels.*)',
       '_paramsAndChangeChanged(params, _change)',
       '_patchNumChanged(_patchRange.patchNum)',
-      '_loadDynamicTabHeaderAndContent(_change, _selectedRevision)',
     ],
 
     keyboardShortcuts() {
@@ -339,6 +338,17 @@
         this._setDiffViewMode();
       });
 
+      Gerrit.awaitPluginsLoaded().then(() => {
+        this._dynamicTabHeaderEndpoints =
+            Gerrit._endpoints.getDynamicEndpoints('change-view-tab-header');
+        this._dynamicTabContentEndpoints =
+            Gerrit._endpoints.getDynamicEndpoints('change-view-tab-content');
+        if (this._dynamicTabContentEndpoints.length
+            !== this._dynamicTabHeaderEndpoints.length) {
+          console.warn('Different number of tab headers and tab content.');
+        }
+      }).then(() => this._setPrimaryTab());
+
       this.addEventListener('comment-save', this._handleCommentSave.bind(this));
       this.addEventListener('comment-refresh', this._reloadDrafts.bind(this));
       this.addEventListener('comment-discard',
@@ -751,17 +761,21 @@
       });
     },
 
+    _setPrimaryTab() {
+      // Selected has to be set after the paper-tabs are visible because
+      // the selected underline depends on calculations made by the browser.
+      this.$.commentTabs.selected = 0;
+      const primaryTabs = this.$$('#primaryTabs');
+      if (primaryTabs) primaryTabs.selected = 0;
+    },
+
     _performPostLoadTasks() {
       this._maybeShowReplyDialog();
       this._maybeShowRevertDialog();
 
       this._sendShowChangeEvent();
 
-      // Selected has to be set after the paper-tabs are visible because
+      this._setPrimaryTab();
-      // the selected underline depends on calculations made by the browser.
-      this.$.commentTabs.selected = 0;
-      const primaryTabs = this.$$('#primaryTabs');
-      if (primaryTabs) primaryTabs.selected = 0;
 
       this.async(() => {
         if (this.viewState.scrollTop) {
@@ -774,41 +788,6 @@
       });
     },
 
-    /**
-     * We use an observer to observe 'change' and 'selectedRevision'
-     * variables. This fixes an issue under Polymer 2 so that the dynamic
-     * plugins loads when these variables load.
-     */
-    _loadDynamicTabHeaderAndContent(change, selectedRevision) {
-      // These vars are unused, but because primaryTabs extension point
-      // uses it, we makes sure we doin't load the plugin until these vars
-      // exist.
-      if (!change || !selectedRevision) return;
-
-      // We cache the _dynamicTabHeaderEndpoints and _dynamicTabContentEndpoints
-      // var so that we doin't keep loading the same dynamic plugin
-      // over and over when 'change' or 'selectedRevision' change.
-      if (this._dynamicTabHeaderEndpoints || this._dynamicTabContentEndpoints) {
-        return;
-      }
-
-      Gerrit.awaitPluginsLoaded().then(() => {
-        this._dynamicTabHeaderEndpoints =
-            Gerrit._endpoints.getDynamicEndpoints('change-view-tab-header');
-        this._dynamicTabContentEndpoints =
-            Gerrit._endpoints.getDynamicEndpoints('change-view-tab-content');
-        if (this._dynamicTabContentEndpoints.length
-            !== this._dynamicTabHeaderEndpoints.length) {
-          console.warn('Different number of tab headers and tab content.');
-        }
-      }).then(() => {
-        // We need a second then(..) to ensure that the dynamic endpoints
-        // are created before we call _performPostLoadTasks(). This ensures it has
-        // enough time before the primary tab gets selected.
-        this._performPostLoadTasks();
-      });
-    },
-
     _paramsAndChangeChanged(value, change) {
       // Polymer 2: check for undefined
       if ([value, change].some(arg => arg === undefined)) {