Add is-empty modifier to file upload (#1383)

* add classes

* add to changelog

CHANGELOG.md

@@ -9,6 +9,7 @@
 * 🎉 #1287 New `.is-invisible` helper
 * 🎉 #1255 New `.is-expanded` modifier for `navbar-item`
 * 🎉 #1384 New `.is-centered` and `.is-right` modifiers for `tags`
+* 🎉 #1383 New `.is-empty` modifier for `file`
 
 ### Improvements
 

sass/elements/form.sass

@@ -269,6 +269,11 @@ $help-size: $size-small !default
     .file-name
       border-bottom-left-radius: 0
       border-top-left-radius: 0
+    &.is-empty
+      .file-cta
+        border-radius: $file-radius
+      .file-name
+        display: none
   &.is-centered
     justify-content: center
   &.is-right