Fix crash on empty snapToOffsets prop to ScrollView

Summary:
When the `snapToOffsets` prop is empty array, the scroll view would crash unexpectly. This diff fixed that by treating empty array prop as null value for `snapToOffsets`.

Changelog:
[Android][Fixed] - Fix crash on empty snapToOffsets array

Reviewed By: makovkastar

Differential Revision: D34802022

fbshipit-source-id: af330512e444081b0cb02b65288ec5cd2bd14205

Author: ryancat

ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactHorizontalScrollViewManager.java

@@ -109,7 +109,7 @@ public void setSnapToAlignment(ReactHorizontalScrollView view, String alignment)
   @ReactProp(name = "snapToOffsets")
   public void setSnapToOffsets(
       ReactHorizontalScrollView view, @Nullable ReadableArray snapToOffsets) {
-    if (snapToOffsets == null) {
+    if (snapToOffsets == null || snapToOffsets.size() == 0) {
       view.setSnapOffsets(null);
       return;
     }

ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewManager.java

@@ -102,7 +102,7 @@ public void setSnapToInterval(ReactScrollView view, float snapToInterval) {
 
   @ReactProp(name = "snapToOffsets")
   public void setSnapToOffsets(ReactScrollView view, @Nullable ReadableArray snapToOffsets) {
-    if (snapToOffsets == null) {
+    if (snapToOffsets == null || snapToOffsets.size() == 0) {
       view.setSnapOffsets(null);
       return;
     }