Use std::atomic for reliminating races in RCTCxxBridge

Author: hakonk

packages/react-native/React/CxxBridge/RCTCxxBridge.mm

@@ -193,7 +193,7 @@ void onBatchComplete() override
 
 @implementation RCTCxxBridge {
   BOOL _didInvalidate;
-  BOOL _moduleRegistryCreated;
+  std::atomic<BOOL> _moduleRegistryCreated;
 
   NSMutableArray<RCTPendingCall> *_pendingCalls;
   std::atomic<NSInteger> _pendingCount;
@@ -220,12 +220,28 @@ @implementation RCTCxxBridge {
   RCTViewRegistry *_viewRegistry_DEPRECATED;
   RCTBundleManager *_bundleManager;
   RCTCallableJSModules *_callableJSModules;
+  std::atomic<BOOL> _loading;
+  std::atomic<BOOL> _valid;
 }
 
 @synthesize bridgeDescription = _bridgeDescription;
-@synthesize loading = _loading;
 @synthesize performanceLogger = _performanceLogger;
-@synthesize valid = _valid;
+
+-(BOOL)isLoading {
+  return _loading;
+}
+
+-(void)setLoading:(BOOL)newValue {
+  _loading = newValue;
+}
+
+-(BOOL)isValid {
+  return _valid;
+}
+
+-(void)setValid:(BOOL)newValue {
+  _valid = newValue;
+}
 
 - (RCTModuleRegistry *)moduleRegistry
 {