Fix the Portal display to not rerender the entire tree

Summary:public
We now wrap the	<RootComponent>	in an <View> where we can control the accessibility at a high level.  This was only used to turn it off for the faded out background view when we show a pop up.

We use setNativeProps instead of setState to avoid the render.	  We really just want to pass this value to the native Android View.

Reviewed By: davidaurelio

Differential Revision: D2928371

fb-gh-sync-id: 19c34471c33650acb526a2f5a02b6070e844e8d0
shipit-source-id: 19c34471c33650acb526a2f5a02b6070e844e8d0

Libraries/ReactIOS/renderApplication.android.js

@@ -73,8 +73,8 @@ var AppContainer = React.createClass({
       return;
     }
 
-    this.setState({
-      rootImportanceForAccessibility: modalVisible ? 'no-hide-descendants' : 'auto',
+    this.refs.accessibilityWrapper.setNativeProps({
+      importantForAccessibility: modalVisible ? 'no-hide-descendants' : 'auto',
     });
   },
 
@@ -85,10 +85,14 @@ var AppContainer = React.createClass({
         ref="main"
         collapsable={!this.state.inspectorVisible}
         style={styles.appContainer}>
-        <RootComponent
-          {...this.props.initialProps}
-          rootTag={this.props.rootTag}
-          importantForAccessibility={this.state.rootImportanceForAccessibility}/>
+        <View
+          ref="accessibilityWrapper"
+          collapsable={true}
+          style={styles.appContainer}>
+          <RootComponent
+            {...this.props.initialProps}
+            rootTag={this.props.rootTag}/>
+        </View>
         <Portal
           onModalVisibilityChanged={this.setRootAccessibility}/>
       </View>;