Make VList in ScrollView warning consider horizontal prop

Summary: It's ok to put VLists in ScrollViews with different scroll directions.

Reviewed By: yungsters

Differential Revision: D16217209

fbshipit-source-id: 7b1c3e93c19867da7414ccda4cda8cc89d25d522

Libraries/Components/ScrollView/ScrollView.js

@@ -585,9 +585,12 @@ function createScrollResponder(
   return scrollResponder;
 }
 
-type ContextType = {||} | null;
+type ContextType = {|horizontal: boolean|} | null;
 const Context = React.createContext<ContextType>(null);
-const standardContext: ContextType = Object.freeze({}); // not null with option value to add more info in the future
+const standardHorizontalContext: ContextType = Object.freeze({
+  horizontal: true,
+});
+const standardVerticalContext: ContextType = Object.freeze({horizontal: false});
 
 /**
  * Component that wraps platform ScrollView while providing
@@ -1022,7 +1025,14 @@ class ScrollView extends React.Component<Props, State> {
       });
     }
     children = (
-      <Context.Provider value={standardContext}>{children}</Context.Provider>
+      <Context.Provider
+        value={
+          this.props.horizontal === true
+            ? standardHorizontalContext
+            : standardVerticalContext
+        }>
+        {children}
+      </Context.Provider>
     );
 
     const hasStickyHeaders =

Libraries/Lists/VirtualizedList.js

@@ -984,12 +984,14 @@ class VirtualizedList extends React.PureComponent<Props, State> {
           {scrollContext => {
             if (
               scrollContext != null &&
+              !scrollContext.horizontal === !this.props.horizontal &&
               !this._hasWarned.nesting &&
               this.context.virtualizedList == null
             ) {
               // TODO (T46547044): use React.warn once 16.9 is sync'd: https://github.com/facebook/react/pull/15170
               console.warn(
-                'VirtualizedLists should never be nested inside a plain ScrollView - use another VirtualizedList-backed container instead.',
+                'VirtualizedLists should never be nested inside plain ScrollViews with the same ' +
+                  'orientation - use another VirtualizedList-backed container instead.',
               );
               this._hasWarned.nesting = true;
             }