Possible solution for Olical#19.

I'm not sure this is the best solution. It does appear to work,
but this solution may have some unintended consequences.

src/Element.js

@@ -235,6 +235,8 @@ Element.prototype.toReact = function (index) {
   var props = clone(this.props)
   props.style = clone(props.style)
 
+  var data = this.__data__
+
   function uniqueKey () {
     return 'faux-dom-' + index
   }
@@ -257,7 +259,7 @@ Element.prototype.toReact = function (index) {
       }
 
       mapValues(listeners, function (listener) {
-        listener(event)
+        listener.call({ '__data__': data }, event)
       })
     }
   }))

test/events.js

@@ -55,3 +55,19 @@ test('removing listeners', function (t) {
   t.plan(1)
   t.equal(eventListeners.onClick.length, 0)
 })
+
+test('event listeners on children', function (t) {
+  var el = mk()
+  var datum = { property: 'value' }
+  var clickValue = 'initial'
+  var join = el.selectAll('.foo')
+    .data([datum])
+  join.enter().append('svg:rect').classed('foo', true)
+    .attr('id', 'foo')
+  join.on('click', function (d) {
+    clickValue = d
+  })
+  el.node().getElementById('foo').toReact().props.onClick()
+  t.plan(1)
+  t.equal(clickValue, datum)
+})