Make views tappable with screen reader

Summary:
Changelog: [Internal]

In paper implementation:
`accessibilityActivate` returns NO in case `onAccessibilityTap` is nil.

In Fabric we have no option to detect whether `onAccessibilityTap` is nil or isn't but we don't want to prevent VoiceOver from tapping an element. This could potentially trigger action associated with element twice.

Let's say you have `onPress` and `onAccessibilityTap`, it will trigger both if you trigger action through VoiceOver.

Reviewed By: shergin

Differential Revision: D18572432

fbshipit-source-id: c5ac002317c798a10045b6f05738299d0ae27456

React/Fabric/Mounting/ComponentViews/View/RCTViewComponentView.mm

@@ -531,26 +531,42 @@ static NSString *RCTRecursiveAccessibilityLabel(UIView *view)
 
 - (BOOL)accessibilityActivate
 {
-  _eventEmitter->onAccessibilityTap();
-  return YES;
+  if (_eventEmitter && _props->onAccessibilityTap) {
+    _eventEmitter->onAccessibilityTap();
+    return YES;
+  } else {
+    return NO;
+  }
 }
 
 - (BOOL)accessibilityPerformMagicTap
 {
-  _eventEmitter->onAccessibilityMagicTap();
-  return YES;
+  if (_eventEmitter && _props->onAccessibilityMagicTap) {
+    _eventEmitter->onAccessibilityMagicTap();
+    return YES;
+  } else {
+    return NO;
+  }
 }
 
 - (BOOL)accessibilityPerformEscape
 {
-  _eventEmitter->onAccessibilityEscape();
-  return YES;
+  if (_eventEmitter && _props->onAccessibilityEscape) {
+    _eventEmitter->onAccessibilityEscape();
+    return YES;
+  } else {
+    return NO;
+  }
 }
 
 - (BOOL)didActivateAccessibilityCustomAction:(UIAccessibilityCustomAction *)action
 {
-  _eventEmitter->onAccessibilityAction(RCTStringFromNSString(action.name));
-  return YES;
+  if (_eventEmitter && _props->onAccessibilityAction) {
+    _eventEmitter->onAccessibilityAction(RCTStringFromNSString(action.name));
+    return YES;
+  } else {
+    return NO;
+  }
 }
 
 - (SharedTouchEventEmitter)touchEventEmitterAtPoint:(CGPoint)point

React/Views/RCTView.m

@@ -393,8 +393,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:unused)
 {
   if ([self performAccessibilityAction:@"activate"]) {
     return YES;
-  }
-  else if (_onAccessibilityTap) {
+  } else if (_onAccessibilityTap) {
     _onAccessibilityTap(nil);
     return YES;
   } else {

ReactCommon/fabric/components/view/accessibility/AccessibilityProps.cpp

@@ -44,6 +44,22 @@ AccessibilityProps::AccessibilityProps(
           rawProps,
           "accessibilityIgnoresInvertColors",
           sourceProps.accessibilityIgnoresInvertColors)),
+      onAccessibilityTap(convertRawProp(
+          rawProps,
+          "onAccessibilityTap",
+          sourceProps.onAccessibilityTap)),
+      onAccessibilityMagicTap(convertRawProp(
+          rawProps,
+          "onAccessibilityMagicTap",
+          sourceProps.onAccessibilityMagicTap)),
+      onAccessibilityEscape(convertRawProp(
+          rawProps,
+          "onAccessibilityEscape",
+          sourceProps.onAccessibilityEscape)),
+      onAccessibilityAction(convertRawProp(
+          rawProps,
+          "onAccessibilityAction",
+          sourceProps.onAccessibilityAction)),
       testId(convertRawProp(rawProps, "testId", sourceProps.testId)) {}
 
 #pragma mark - DebugStringConvertible

ReactCommon/fabric/components/view/accessibility/AccessibilityProps.h

@@ -32,6 +32,11 @@ class AccessibilityProps {
   bool const accessibilityViewIsModal{false};
   bool const accessibilityElementsHidden{false};
   bool const accessibilityIgnoresInvertColors{false};
+  bool const onAccessibilityTap{};
+  bool const onAccessibilityMagicTap{};
+  bool const onAccessibilityEscape{};
+  bool const onAccessibilityAction{};
+
   std::string const testId{""};
 
 #pragma mark - DebugStringConvertible