refactor(toast): remove cssClass from ToastButton (#28977)

BREAKING CHANGE:
The `cssClass` property has been removed from `ToastButton`

BREAKING.md

@@ -162,3 +162,9 @@ For more information on the dynamic font, refer to the [Dynamic Font Scaling doc
 - `ion-picker` and `ion-picker-column` have been renamed to `ion-picker-legacy` and `ion-picker-legacy-column`, respectively. This change was made to accommodate the new inline picker component while allowing developers to continue to use the legacy picker during this migration period.
   - Only the component names have been changed. Usages such as `ion-picker` or `IonPicker` should be changed to `ion-picker-legacy` and `IonPickerLegacy`, respectively.
   - Non-component usages such as `pickerController` or `useIonPicker` remain unchanged. The new picker displays inline with your page content and does not have equivalents for these non-component usages.
+
+<h4 id="version-8x-toast">Toast</h4>
+
+- `cssClass` has been removed from the `ToastButton` interface. This was previously used to apply a custom class to the toast buttons. Developers can use the "button" shadow part to style the buttons.
+
+For more information on styling toast buttons, refer to the [Toast Theming documentation](https://ionicframework.com/docs/api/toast#theming).

core/src/components/toast/toast-interface.ts

@@ -27,18 +27,12 @@ export interface ToastOptions {
 
 export type ToastLayout = 'baseline' | 'stacked';
 
-// TODO FW-4923 remove cssClass property
-
 export interface ToastButton {
   text?: string;
   icon?: string;
   side?: 'start' | 'end';
   role?: 'cancel' | string;
 
-  /**
-   * @deprecated Use the toast button's CSS Shadow Parts instead.
-   */
-  cssClass?: string | string[];
   htmlAttributes?: { [key: string]: any };
   handler?: () => boolean | void | Promise<boolean | void>;
 }

core/src/components/toast/toast.tsx

@@ -778,7 +778,6 @@ const buttonClass = (button: ToastButton): CssClassMap => {
     [`toast-button-${button.role}`]: button.role !== undefined,
     'ion-focusable': true,
     'ion-activatable': true,
-    ...getClassMap(button.cssClass),
   };
 };