Fix bug when given non-lower-cased types

Author: wooorm

Diff for: index.js

@@ -175,6 +175,10 @@ function addChild(nodes, value) {
 function isNode(tagName, value) {
     var type = value.type;
 
+    if (typeof type === 'string') {
+        type = type.toLowerCase();
+    }
+
     if (tagName === 'input' || !type || typeof type !== 'string') {
         return false;
     }

Diff for: test.js

@@ -722,6 +722,24 @@ test('hastscript', function (t) {
             'a button has a valid type'
         );
 
+        st.deepEqual(
+            h('button', {
+                'type': 'BUTTON',
+                'value': 'Send'
+            }),
+            {
+                'type': 'element',
+                'tagName': 'button',
+                'properties': {
+                    'type': 'BUTTON',
+                    'value': 'Send'
+                },
+                'children': []
+            },
+            'should *not* allow omitting `properties` when ' +
+            'a button has a valid non-lowercase type'
+        );
+
         st.deepEqual(
             h('button', {
                 'type': 'menu',