Android: Expose Image's onError event to JavaScript

Summary:
iOS supports an Image onError event. Android was firing the event but it was never reaching JavaScript because Android didn't include this event in `getExportedCustomDirectEventTypeConstants`.

**Test plan (required)**

Verified that the `onError` event now fires in a test app.

My team uses this change in our app.

Adam Comella
Microsoft Corp.
Closes https://github.com/facebook/react-native/pull/10902

Differential Revision: D4180149

Pulled By: ericvicenti

fbshipit-source-id: 4bf0b9aa7dc221d838d7b6b3e88bb47196dcadef

Libraries/Image/Image.android.js

@@ -119,6 +119,10 @@ var Image = React.createClass({
      * Invoked on load start
      */
     onLoadStart: PropTypes.func,
+    /**
+     * Invoked on load error
+     */
+    onError: PropTypes.func,
     /**
      * Invoked when load completes successfully
      */
@@ -284,10 +288,10 @@ var Image = React.createClass({
         sources = source;
       }
 
-      const {onLoadStart, onLoad, onLoadEnd} = this.props;
+      const {onLoadStart, onLoad, onLoadEnd, onError} = this.props;
       const nativeProps = merge(this.props, {
         style,
-        shouldNotifyLoadEvents: !!(onLoadStart || onLoad || onLoadEnd),
+        shouldNotifyLoadEvents: !!(onLoadStart || onLoad || onLoadEnd || onError),
         src: sources,
         loadingIndicatorSrc: loadingIndicatorSource ? loadingIndicatorSource.uri : null,
       });

Libraries/Image/Image.ios.js

@@ -255,7 +255,6 @@ const Image = React.createClass({
     onProgress: PropTypes.func,
     /**
      * Invoked on load error with `{nativeEvent: {error}}`.
-     * @platform ios
      */
     onError: PropTypes.func,
     /**

ReactAndroid/src/main/java/com/facebook/react/views/image/ReactImageManager.java

@@ -178,6 +178,8 @@ public class ReactImageManager extends SimpleViewManager<ReactImageView> {
         MapBuilder.of("registrationName", "onLoadStart"),
       ImageLoadEvent.eventNameForType(ImageLoadEvent.ON_LOAD),
         MapBuilder.of("registrationName", "onLoad"),
+      ImageLoadEvent.eventNameForType(ImageLoadEvent.ON_ERROR),
+        MapBuilder.of("registrationName", "onError"),
       ImageLoadEvent.eventNameForType(ImageLoadEvent.ON_LOAD_END),
         MapBuilder.of("registrationName", "onLoadEnd"));
   }