chore: move null config check into mat-using-mdc-typography (#15906)

src/material-experimental/mdc-button/_mdc-button.scss

@@ -7,12 +7,7 @@
 }
 
 @mixin mat-button-typography-mdc($config) {
-  @if config {
-    @include mat-using-mdc-typography($config) {
-      // TODO: MDC typography styles here.
-    }
-  }
-  @else {
+  @include mat-using-mdc-typography($config) {
     // TODO: MDC typography styles here.
   }
 }

src/material-experimental/mdc-card/_mdc-card.scss

@@ -7,12 +7,7 @@
 }
 
 @mixin mat-card-typography-mdc($config) {
-  @if config {
-    @include mat-using-mdc-typography($config) {
-      // TODO: MDC typography styles here.
-    }
-  }
-  @else {
+  @include mat-using-mdc-typography($config) {
     // TODO: MDC typography styles here.
   }
 }

src/material-experimental/mdc-checkbox/_mdc-checkbox.scss

@@ -66,13 +66,7 @@
 }
 
 @mixin mat-checkbox-typography-mdc($config: null) {
-  @if $config {
-    @include mat-using-mdc-typography($config) {
-      @include mdc-checkbox-without-ripple($query: $mat-typography-styles-query);
-      @include mdc-form-field-core-styles($query: $mat-typography-styles-query);
-    }
-  }
-  @else {
+  @include mat-using-mdc-typography($config) {
     @include mdc-checkbox-without-ripple($query: $mat-typography-styles-query);
     @include mdc-form-field-core-styles($query: $mat-typography-styles-query);
   }

src/material-experimental/mdc-helpers/_mdc-helpers.scss

@@ -199,7 +199,9 @@ $mat-typography-level-mappings: (
   $orig-mdc-typography-styles: $mdc-typography-styles;
 
   // Set new values based on the given Angular Material typography configuration.
-  $mdc-typography-styles: mat-typography-config-to-mdc($config) !global;
+  @if $config {
+    $mdc-typography-styles: mat-typography-config-to-mdc($config) !global;
+  }
 
   // Apply given rules.
   @content;

src/material-experimental/mdc-menu/_mdc-menu.scss

@@ -39,21 +39,12 @@
 }
 
 @mixin mat-menu-typography-mdc($config) {
-  @if config {
-    @include mat-using-mdc-typography($config) {
-      @include mdc-menu-surface-core-styles($mat-typography-styles-query);
-
-      .mat-mdc-menu-content {
-        // Note that we include this private mixin, because the public
-        // one adds a bunch of styles that we aren't using for the menu.
-        @include mdc-list-base_($mat-typography-styles-query);
-      }
-    }
-  }
-  @else {
+  @include mat-using-mdc-typography($config) {
     @include mdc-menu-surface-core-styles($mat-typography-styles-query);
 
     .mat-mdc-menu-content {
+      // Note that we include this private mixin, because the public
+      // one adds a bunch of styles that we aren't using for the menu.
       @include mdc-list-base_($mat-typography-styles-query);
     }
   }

src/material-experimental/mdc-radio/_mdc-radio.scss

@@ -7,12 +7,7 @@
 }
 
 @mixin mat-radio-typography-mdc($config) {
-  @if config {
-    @include mat-using-mdc-typography($config) {
-      // TODO: MDC typography styles here.
-    }
-  }
-  @else {
+  @include mat-using-mdc-typography($config) {
     // TODO: MDC typography styles here.
   }
 }

src/material-experimental/mdc-slide-toggle/_mdc-slide-toggle.scss

@@ -7,12 +7,7 @@
 }
 
 @mixin mat-slide-toggle-typography-mdc($config) {
-  @if config {
-    @include mat-using-mdc-typography($config) {
-      // TODO: MDC typography styles here.
-    }
-  }
-  @else {
+  @include mat-using-mdc-typography($config) {
     // TODO: MDC typography styles here.
   }
 }