Fix retain cycle

Summary:
public

This fixes the following circular reference:

RCTComponentData
-> _bridge -> RCTBatchedBridge
-> _moduleDataByName -> __NSDictionaryI
-> RCTModuleData
-> _instance -> RCTUIManager
-> _componentDataByName -> __NSDictionaryI
-> RCTComponentData

Reviewed By: javache

Differential Revision: D2744742

fb-gh-sync-id: c282786f4dfb550185bc03d3e5e3d03048664c21

React/Views/RCTComponentData.h

@@ -21,7 +21,7 @@
 
 @property (nonatomic, readonly) Class managerClass;
 @property (nonatomic, copy, readonly) NSString *name;
-@property (nonatomic, strong, readonly) RCTViewManager *manager;
+@property (nonatomic, weak, readonly) RCTViewManager *manager;
 
 - (instancetype)initWithManagerClass:(Class)managerClass
                               bridge:(RCTBridge *)bridge NS_DESIGNATED_INITIALIZER;

React/Views/RCTComponentData.m

@@ -44,7 +44,7 @@ typedef void (^RCTPropBlock)(id<RCTComponent> view, id json);
   RCTShadowView *_defaultShadowView;
   NSMutableDictionary<NSString *, RCTPropBlock> *_viewPropBlocks;
   NSMutableDictionary<NSString *, RCTPropBlock> *_shadowPropBlocks;
-  RCTBridge *_bridge;
+  __weak RCTBridge *_bridge;
 }
 
 @synthesize manager = _manager;