fix(material/snack-bar): use inverse primary for button color

Author: Andrew Seguin

src/material/snack-bar/_m2-snack-bar.scss

@@ -12,18 +12,12 @@
 
 // Tokens that can be configured through Angular Material's color theming API.
 @function get-color-tokens($theme) {
-  $is-dark: inspection.get-theme-type($theme) == dark;
   $system: m2-utils.get-system($theme);
 
   @return (
     snack-bar-container-color: map.get($system, inverse-surface),
     snack-bar-supporting-text-color: map.get($system, inverse-on-surface),
-    snack-bar-button-color:
-      if(
-        $is-dark,
-        inspection.get-theme-color($theme, primary, 500),
-        inspection.get-theme-color($theme, primary, 100)
-      )
+    snack-bar-button-color: map.get($system, inverse-primary),
   );
 }