Remove redundant helper function

app/src/main/java/eu/kanade/tachiyomi/ui/browse/BrowseController.kt

@@ -95,10 +95,6 @@ class BrowseController :
         tabs.getTabAt(EXTENSIONS_CONTROLLER)?.removeBadge()
     }
 
-    fun pushController(transaction: RouterTransaction) {
-        router.pushController(transaction)
-    }
-
     fun setExtensionUpdateBadge() {
         activity?.tabs?.apply {
             val updates = preferences.extensionUpdatesCount().get()

app/src/main/java/eu/kanade/tachiyomi/ui/browse/extension/ExtensionController.kt

@@ -87,7 +87,7 @@ open class ExtensionController :
         when (item.itemId) {
             R.id.action_search -> expandActionViewFromInteraction = true
             R.id.action_settings -> {
-                (parentController as BrowseController).pushController(
+                parentController!!.router.pushController(
                     ExtensionFilterController().withFadeTransaction()
                 )
             }
@@ -167,7 +167,7 @@ open class ExtensionController :
 
     private fun openDetails(extension: Extension.Installed) {
         val controller = ExtensionDetailsController(extension.pkgName)
-        (parentController as BrowseController).pushController(controller.withFadeTransaction())
+        parentController!!.router.pushController(controller.withFadeTransaction())
     }
 
     private fun openTrustDialog(extension: Extension.Untrusted) {

app/src/main/java/eu/kanade/tachiyomi/ui/browse/source/SourceController.kt

@@ -185,7 +185,7 @@ class SourceController :
      */
     private fun openCatalogue(source: CatalogueSource, controller: BrowseSourceController) {
         preferences.lastUsedCatalogueSource().set(source.id)
-        (parentController as BrowseController).pushController(controller.withFadeTransaction())
+        parentController!!.router.pushController(controller.withFadeTransaction())
     }
 
     /**
@@ -214,7 +214,7 @@ class SourceController :
     }
 
     private fun performGlobalSearch(query: String) {
-        (parentController as BrowseController).pushController(
+        parentController!!.router.pushController(
             GlobalSearchController(query).withFadeTransaction()
         )
     }
@@ -229,7 +229,7 @@ class SourceController :
         when (item.itemId) {
             // Initialize option to open catalogue settings.
             R.id.action_settings -> {
-                (parentController as BrowseController).pushController(
+                parentController!!.router.pushController(
                     SettingsSourcesController().withFadeTransaction()
                 )
             }