Update Dartdoc so it is aware of the new createPlatformViewSlot funct…

…ion everywhere.

lib/web_ui/lib/src/engine/platform_views/content_manager.dart

@@ -46,7 +46,7 @@ class PlatformViewManager {
 
   /// Returns `true` if the passed in `viewId` has been rendered (and not disposed) before.
   ///
-  /// See [renderContent] and [renderSlot] to understand how platform views are
+  /// See [renderContent] and [createPlatformViewSlot] to understand how platform views are
   /// rendered.
   bool knowsViewId(int viewId) {
     return _contents.containsKey(viewId);

lib/web_ui/lib/src/engine/platform_views/message_handler.dart

@@ -26,9 +26,8 @@ typedef PlatformViewContentHandler = void Function(html.Element);
 /// function (passed from the outside) will decide where in the DOM to inject
 /// said content.
 ///
-/// The rendering/compositing of Platform Views will have access to the other "half"
-/// of the Platform View: the `slot`, through the shared `contentManager` object,
-/// through its [PlatformViewManager.renderSlot] method.
+/// The rendering/compositing of Platform Views can create the other "half" of a
+/// Platform View: the `slot`, through the [createPlatformViewSlot] method.
 ///
 /// When a Platform View is disposed of, it is removed from the cache (and DOM)
 /// directly by the `contentManager`. The canvaskit rendering backend needs to do

lib/web_ui/lib/src/engine/platform_views/slots.dart

@@ -4,7 +4,7 @@
 
 part of engine;
 
-/// Returns the name of a Slot from its viewId.
+/// Returns the name of a slot from its `viewId`.
 ///
 /// This is used by the [renderContent] function of the [PlatformViewManager]
 /// class, and the [createPlatformViewSlot] method below, to keep the slot name