Added constraint of child type to touchablewithoutfeedback

Summary:
Added constraint of child type to touchablewithoutfeedback to match touchablehighlight (this would have failed silently previously), also added the cloneWithProps as by note of @vjeux
Closes #517
Github Author: Daniele Zannotti <d.zannotti@me.com>

Test Plan: Imported from GitHub, without a `Test Plan:` line.

Libraries/Components/Touchable/TouchableWithoutFeedback.js

@@ -13,8 +13,10 @@
 
 var React = require('React');
 var Touchable = require('Touchable');
-
+var keyOf = require('keyOf');
 var onlyChild = require('onlyChild');
+var cloneWithProps = require('cloneWithProps');
+var ensureComponentIsNative = require('ensureComponentIsNative');
 
 /**
  * When the scroll view is disabled, this defines how far your touch may move
@@ -49,6 +51,14 @@ var TouchableWithoutFeedback = React.createClass({
     return this.touchableGetInitialState();
   },
 
+  componentDidMount: function() {
+    ensureComponentIsNative(this.refs[CHILD_REF]);
+  },
+
+  componentDidUpdate: function() {
+    ensureComponentIsNative(this.refs[CHILD_REF]);
+  },
+
   /**
    * `Touchable.Mixin` self callbacks. The mixin will invoke these if they are
    * defined on your component.
@@ -78,8 +88,15 @@ var TouchableWithoutFeedback = React.createClass({
   },
 
   render: function(): ReactElement {
-    // Note(vjeux): use cloneWithProps once React has been upgraded
-    var child = onlyChild(this.props.children);
+    var child = cloneWithProps(
+      onlyChild(this.props.children),
+      {
+        ref: CHILD_REF,
+        accessible: true,
+        testID: this.props.testID,
+      }
+    );
+
     // Note(avik): remove dynamic typecast once Flow has been upgraded
     return (React: any).cloneElement(child, {
       accessible: true,
@@ -94,4 +111,6 @@ var TouchableWithoutFeedback = React.createClass({
   }
 });
 
+var CHILD_REF = keyOf({childRef: null});
+
 module.exports = TouchableWithoutFeedback;