Move ScrollView's contentOffset to common props

Summary:
ScrollView's contentOffset prop was assumed to be iOS only, but in reality it is supported on Android as well: https://fburl.com/code/nuxpjpth

Changelog:
[General] - Move ScrollView's contentOffset to common props

Reviewed By: yungsters

Differential Revision: D36219604

fbshipit-source-id: f41679fd2ce7971a30129e0d91ae9f32b9cf756e

Libraries/Components/ScrollView/ScrollView.js

@@ -190,12 +190,6 @@ type IOSProps = $ReadOnly<{|
    * @platform ios
    */
   contentInset?: ?EdgeInsetsProp,
-  /**
-   * Used to manually set the starting scroll offset.
-   * The default value is `{x: 0, y: 0}`.
-   * @platform ios
-   */
-  contentOffset?: ?PointProp,
   /**
    * When true, the scroll view bounces when it reaches the end of the
    * content if the content is larger then the scroll view along the axis of
@@ -457,6 +451,11 @@ export type Props = $ReadOnly<{|
    * ```
    */
   contentContainerStyle?: ?ViewStyleProp,
+  /**
+   * Used to manually set the starting scroll offset.
+   * The default value is `{x: 0, y: 0}`.
+   */
+  contentOffset?: ?PointProp,
   /**
    * When true, the scroll view stops on the next index (in relation to scroll
    * position at release) regardless of how fast the gesture is. This can be

packages/rn-tester/js/examples/ScrollView/ScrollViewExample.js

@@ -391,6 +391,13 @@ const examples = ([
       return <SnapToOptions />;
     },
   },
+  {
+    title: '<ScrollView> (contentOffset = {x: 100, y: 0})\n',
+    description: 'Initial contentOffset can be set on ScrollView.',
+    render: function (): React.Node {
+      return <ContentOffsetList />;
+    },
+  },
 ]: Array<RNTesterModuleExample>);
 
 if (Platform.OS === 'ios') {
@@ -411,13 +418,6 @@ if (Platform.OS === 'ios') {
       return <CenterContentList />;
     },
   });
-  examples.push({
-    title: '<ScrollView> (contentOffset = {x: 100, y: 0})\n',
-    description: 'Initial contentOffset can be set on ScrollView.',
-    render: function (): React.Node {
-      return <ContentOffsetList />;
-    },
-  });
   examples.push({
     title: '<ScrollView> Always Bounces\n',
     description: 'Always bounce vertically or horizontally.',