Issues/#1689 text input warning

Summary:
This should close issue 1689. Using Object.assign to pass Flow checks.
Closes #1956
Github Author: Matt Revell <mattrevell82@me.com>

Author: admmasters

Libraries/Components/TextInput/TextInput.js

@@ -411,7 +411,7 @@ var TextInput = React.createClass({
   _renderIOS: function() {
     var textContainer;
 
-    var props = this.props;
+    var props = Object.assign({},this.props);
     props.style = [styles.input, this.props.style];
 
     if (!props.multiline) {