Fix #175 'Content is laid out repeatedly during expand animation' (#180)

* Fix #175 'Content is laid out repeatedly during expand animation'

* Format code using Prettier

Collapsible.js

@@ -1,6 +1,6 @@
 import React, { Component } from 'react';
 import PropTypes from 'prop-types';
-import { Animated, Easing } from 'react-native';
+import { Animated, Easing, View } from 'react-native';
 import { ViewPropTypes } from './config';
 
 const ANIMATED_EASING_PREFIXES = ['easeInOut', 'easeOut', 'easeIn'];
@@ -198,7 +198,9 @@ export default class Collapsible extends Component {
           style={[this.props.style, contentStyle]}
           onLayout={this.state.animating ? undefined : this._handleLayoutChange}
         >
-          {this.props.children}
+          <View style={{ height: measured ? contentHeight : null }}>
+            {this.props.children}
+          </View>
         </Animated.View>
       </Animated.View>
     );