Support multiple select fields in form submissions

example/forms.html

@@ -56,7 +56,7 @@
         <br />
 
         <label for="get-form-select">Select list:</label>
-        <select name="select" id="get-form-select">
+        <select multiple name="select" id="get-form-select">
           <option>
             Option 1
           </option>
@@ -119,7 +119,7 @@
         <br />
 
         <label for="post-form-select">Select list:</label>
-        <select name="select" id="post-form-select">
+        <select multiple name="select" id="post-form-select">
           <option>
             Option 1
           </option>