fix(snackbar): match spec animations more closely

- Uses the standard curve for both enter and exit animations
- Use long animation duration as spec shows

Author: willshowell

src/lib/snack-bar/snack-bar-container.ts

@@ -42,8 +42,8 @@ export type SnackBarState = 'initial' | 'visible' | 'complete' | 'void';
 
 // TODO(jelbourn): we can't use constants from animation.ts here because you can't use
 // a text interpolation in anything that is analyzed statically with ngc (for AoT compile).
-export const SHOW_ANIMATION = '225ms cubic-bezier(0.4,0.0,1,1)';
-export const HIDE_ANIMATION = '195ms cubic-bezier(0.0,0.0,0.2,1)';
+export const SHOW_ANIMATION = '375ms cubic-bezier(0.4,0.0,0.2,1)';
+export const HIDE_ANIMATION = SHOW_ANIMATION;
 
 /**
  * Internal component that wraps user-provided snack bar content.