chore: update placeholder-shown test

Author: Marukome0743

lib/hacks/placeholder-shown.js

@@ -5,10 +5,11 @@ class PlaceholderShown extends Selector {
    * Return different selectors depend on prefix
    */
   prefixed(prefix) {
+    if (prefix === '-ms-') {
+      return ':-ms-input-placeholder'
+    }
     if (prefix === '-moz-') {
       return ':-moz-placeholder'
-    } else if (prefix === '-ms-') {
-      return ':-ms-input-placeholder'
     }
     return `:${prefix}placeholder-shown`
   }

test/autoprefixer.test.js

@@ -64,7 +64,7 @@ let backdroper = autoprefixer({
   overrideBrowserslist: ['IE >= 11', 'Chrome < 32', 'Safari >= 15.4']
 })
 let placeholderShowner = autoprefixer({
-  overrideBrowserslist: ['IE >= 10']
+  overrideBrowserslist: ['IE >= 10', 'Firefox >= 4']
 })
 let transitionSpec = autoprefixer({
   overrideBrowserslist: ['Chrome > 19', 'Firefox 14', 'IE 10', 'Opera 12']

test/cases/placeholder-shown.out.css

@@ -1,3 +1,6 @@
+:-moz-placeholder {
+  background: #eee
+}
 :-ms-input-placeholder {
   background: #eee
 }