Don’t allow overscroll

The iOS change seems to have a side effect on Android of adding  an“Edge Effect” to the web view whenever dragging a block. (Edge effects are the grey curved shadow that appears at the top or bottom of a container when you overscroll. When you drag a block they appear at the top or bottom of the screen)

Adding the `android:overScrollMode=“never”` attribute to the webview means the edge effect doesn’t appear.

android/ScratchJr/app/src/main/res/layout/activity_scratch_jr.xml

@@ -11,6 +11,7 @@
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:layout_centerInParent="true"
+        android:overScrollMode="never"
        />
     
 </RelativeLayout>