fix(Stepper): fix mobile safari page scroll down issue (#7701)

src/stepper/index.js

@@ -268,6 +268,14 @@ export default createComponent({
         preventDefault(event);
       }
     },
+
+    onMousedown(event) {
+      // fix mobile safari page scroll down issue
+      // see: https://github.com/youzan/vant/issues/7690
+      if (this.disableInput) {
+        event.preventDefault();
+      }
+    },
   },
 
   render() {
@@ -315,6 +323,7 @@ export default createComponent({
           onInput={this.onInput}
           onFocus={this.onFocus}
           onBlur={this.onBlur}
+          onMousedown={this.onMousedown}
         />
         <button
           vShow={this.showPlus}