iOS: Attempt to load lazy modules when asked from native

Summary:
Previously, asking for an instance of NativeModule from the native side gave `nil` if the lazy modules have not been loaded, which is not consistent with the access from JS. This at least attempts to force load the lazy modules when asked from native.

p.s. one asks for a module by doing `[bridge moduleForClass:[FooBar class]]`.

Reviewed By: spredolac

Differential Revision: D12931640

fbshipit-source-id: 15d2dc574067d3386ef921512ce4bc837749dabd

React/Base/RCTBridge.m

@@ -243,7 +243,11 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 
 - (id)moduleForClass:(Class)moduleClass
 {
-  return [self moduleForName:RCTBridgeModuleNameForClass(moduleClass)];
+  id module = [self.batchedBridge moduleForClass:moduleClass];
+  if (!module) {
+    module = [self moduleForName:RCTBridgeModuleNameForClass(moduleClass)];
+  }
+  return module;
 }
 
 - (NSArray *)modulesConformingToProtocol:(Protocol *)protocol

React/CxxBridge/RCTCxxBridge.mm

@@ -444,6 +444,21 @@ struct RCTInstanceCallback : public InstanceCallback {
   return _moduleDataByName[RCTBridgeModuleNameForClass(moduleClass)].hasInstance;
 }
 
+- (id)moduleForClass:(Class)moduleClass
+{
+  NSString *moduleName = RCTBridgeModuleNameForClass(moduleClass);
+  RCTModuleData *moduleData = _moduleDataByName[moduleName];
+  if (moduleData) {
+    return moduleData.instance;
+  }
+
+  // Module may not be loaded yet, so attempt to force load it here.
+  RCTAssert([moduleClass conformsToProtocol:@protocol(RCTBridgeModule)], @"Asking for a NativeModule that doesn't conform to RCTBridgeModule: %@", NSStringFromClass(moduleClass));
+  [self registerAdditionalModuleClasses:@[moduleClass]];
+
+  return _moduleDataByName[moduleName].instance;
+}
+
 - (std::shared_ptr<ModuleRegistry>)_buildModuleRegistryUnlocked
 {
   if (!self.valid) {