Add destroy hook directly on vnodes

snabbdom.js

@@ -97,7 +97,8 @@ function init(modules) {
   }
 
   function invokeDestroyHook(vnode) {
-    var i, j;
+    var i = vnode.data.hook, j;
+    if (!isUndef(i) && !isUndef(j = i.destroy)) j(vnode);
     for (i = 0; i < destroyCbs.length; ++i) destroyCbs[i](vnode);
     if (!isUndef(vnode.children)) {
       for (j = 0; j < vnode.children.length; ++j) {

test/core.js

@@ -526,6 +526,20 @@ describe('snabbdom', function() {
         assert.deepEqual(result, ['pre', 'post']);
       });
       it('invokes `destroy` hook for all removed children', function() {
+        var result = [];
+        function cb(vnode) { result.push(vnode); }
+        var vnode1 = h('div', [
+          h('span', 'First sibling'),
+          h('div', [
+            h('span', {hook: {destroy: cb}}, 'Child 1'),
+            h('span', 'Child 2'),
+          ]),
+        ]);
+        patch(vnode0, vnode1);
+        patch(vnode1, vnode0);
+        assert.equal(result.length, 1);
+      });
+      it('invokes `destroy` module hook for all removed children', function() {
         var created = 0;
         var destroyed = 0;
         var patch = snabbdom.init([