### Is this a regression? - [ ] Yes, this behavior used to work in the previous version ### The previous version in which this bug was not present was 14 ### Description The class mat-tooltip isn't equal to mat-mdc-tooltip. ### Reproduction StackBlitz link: Steps to reproduce: 1. 2. ### Expected Behavior the right class should be - 'mdc-tooltip__surface' ### Actual Behavior replace mat-tooltip to mat-mdc-tooltip ### Environment - Angular: - CDK/Material: - Browser(s): - Operating System (e.g. Windows, macOS, Ubuntu):