Fix clone of props for legacy interop component

Summary:
Changelog: [internal]

Cloning of `LegacyViewManagerInteropViewProps` causes loss of `sourceProps.otherProps` if the cloning happens before shadow node is mounted. This was happening in WebView and callback `onLoadEnd` was dropped because of this.

Reviewed By: JoshuaGross

Differential Revision: D25474581

fbshipit-source-id: 74d7c5cd32b7318bb99306c82bc8b5e5eab63db2

ReactCommon/react/renderer/components/legacyviewmanagerinterop/LegacyViewManagerInteropViewProps.cpp

@@ -10,10 +10,20 @@
 namespace facebook {
 namespace react {
 
+static folly::dynamic recursiveMerge(
+    folly::dynamic const &lhs,
+    folly::dynamic const &rhs) {
+  auto copy = lhs;
+  copy.merge_patch(rhs);
+  return copy;
+}
+
 LegacyViewManagerInteropViewProps::LegacyViewManagerInteropViewProps(
     const LegacyViewManagerInteropViewProps &sourceProps,
     const RawProps &rawProps)
-    : ViewProps(sourceProps, rawProps), otherProps((folly::dynamic)rawProps) {}
+    : ViewProps(sourceProps, rawProps),
+      otherProps(
+          recursiveMerge(sourceProps.otherProps, (folly::dynamic)rawProps)) {}
 
 } // namespace react
 } // namespace facebook