fix(MdStep): set tabindex for not active step (#2215)

* fix(MdStep): set tabindex for not active step

* feat(MdStep): add v-show to hide content

Co-authored-by: Samuell1 <[email protected]>

Author: oliver-ni

src/components/MdSteppers/MdStep.vue

@@ -2,7 +2,7 @@
   <div class="md-stepper">
     <md-step-header v-if="MdSteppers.isVertical" :index="id" />
 
-    <div class="md-stepper-content" :class="{ 'md-active': !MdSteppers.syncRoute && id === MdSteppers.activeStep }">
+    <div :class="['md-stepper-content', { 'md-active': isActive }]" :tabindex="tabIndex" v-show="isActive">
       <slot />
     </div>
   </div>
@@ -43,6 +43,16 @@
         }
       }
     },
+    computed: {
+      isActive () {
+        return this.id === this.MdSteppers.activeStep
+      },
+      tabIndex () {
+        return !this.isActive
+          ? -1
+          : false
+      }
+    },
     methods: {
       getPropValues () {
         const propNames = Object.keys(this.$options.props)