tweak

Author: adolgachev

src/material/stepper/stepper.html

@@ -55,7 +55,9 @@
             [class.mat-stepper-vertical-line]="!$last"
             [class.mat-vertical-content-container-active]="selectedIndex === $index"
             [attr.inert]="selectedIndex === $index ? null : ''">
-            <div class="mat-vertical-stepper-content"
+            <div 
+              class="mat-vertical-stepper-content"
+              role="region"
               [id]="_getStepContentId($index)"
               [attr.aria-labelledby]="_getStepLabelId($index)">
               <div class="mat-vertical-content">