Scroll multiline textinputs when focused

Summary:
Currently, text inputs do not scroll when inside other components like scroll
views. This fixes it by blocking any parent native component from taking the
responder when the text input is focused and is being scrolled. This fixes the
previous implementation, where the scroll view was not able to scroll on top of
other text inputs, even though they were not focused.
This makes the component similar to it's ios counterpart.

Reviewed By: foghina

Differential Revision: D3735237

fbshipit-source-id: 0e56b2bbd3f5636540b4c3cc7cc13aa0f4d2737e

Libraries/Components/TextInput/TextInput.js

@@ -691,6 +691,7 @@ const TextInput = React.createClass({
       <TouchableWithoutFeedback
         onLayout={this.props.onLayout}
         onPress={this._onPress}
+        shouldBlockResponder={this.isFocused}
         accessible={this.props.accessible}
         accessibilityLabel={this.props.accessibilityLabel}
         accessibilityComponentType={this.props.accessibilityComponentType}

Libraries/Components/Touchable/Touchable.js

@@ -396,6 +396,7 @@ var TouchableMixin = {
       this._handleLongDelay.bind(this, e),
       longDelayMS + delayMS
     );
+    return this.props.shouldBlockResponder && this.props.shouldBlockResponder();
   },
 
   /**