Add cancelable prop, use mixed return type for event handlers

Summary:
Changelog:
[General][Added] Added `cancelable` prop to Pressable.
[General][Changed] Event handlers return mixed type instead of void.

Reviewed By: yungsters

Differential Revision: D26432837

fbshipit-source-id: c7bafdec085d08a06e859b45bff91a3b07d747ed

Libraries/Components/Pressable/Pressable.js

@@ -51,6 +51,12 @@ type Props = $ReadOnly<{|
   importantForAccessibility?: ?('auto' | 'yes' | 'no' | 'no-hide-descendants'),
   onAccessibilityAction?: ?(event: AccessibilityActionEvent) => mixed,
 
+  /**
+   * Whether a press gesture can be interrupted by a parent gesture such as a
+   * scroll event. Defaults to true.
+   */
+  cancelable?: ?boolean,
+
   /**
    * Either children or a render prop that receives a boolean reflecting whether
    * the component is currently pressed.
@@ -81,27 +87,27 @@ type Props = $ReadOnly<{|
   /**
    * Called when this view's layout changes.
    */
-  onLayout?: ?(event: LayoutEvent) => void,
+  onLayout?: ?(event: LayoutEvent) => mixed,
 
   /**
    * Called when a long-tap gesture is detected.
    */
-  onLongPress?: ?(event: PressEvent) => void,
+  onLongPress?: ?(event: PressEvent) => mixed,
 
   /**
    * Called when a single tap gesture is detected.
    */
-  onPress?: ?(event: PressEvent) => void,
+  onPress?: ?(event: PressEvent) => mixed,
 
   /**
    * Called when a touch is engaged before `onPress`.
    */
-  onPressIn?: ?(event: PressEvent) => void,
+  onPressIn?: ?(event: PressEvent) => mixed,
 
   /**
    * Called when a touch is released before `onPress`.
    */
-  onPressOut?: ?(event: PressEvent) => void,
+  onPressOut?: ?(event: PressEvent) => mixed,
 
   /**
    * Either view styles or a function that receives a boolean reflecting whether
@@ -144,6 +150,7 @@ function Pressable(props: Props, forwardedRef): React.Node {
     accessible,
     android_disableSound,
     android_ripple,
+    cancelable,
     children,
     delayLongPress,
     disabled,
@@ -184,6 +191,7 @@ function Pressable(props: Props, forwardedRef): React.Node {
 
   const config = useMemo(
     () => ({
+      cancelable,
       disabled,
       hitSlop,
       pressRectOffset: pressRetentionOffset,
@@ -215,6 +223,7 @@ function Pressable(props: Props, forwardedRef): React.Node {
     [
       android_disableSound,
       android_rippleConfig,
+      cancelable,
       delayLongPress,
       disabled,
       hitSlop,