removed `coalescingKey` from events (2/7)

Summary:
This property was never used, so I'm removing it.

public
___
//This diff is part of a larger stack. For high level overview what's going on jump to D2884593.//

Reviewed By: javache

Differential Revision: D2884587

fb-gh-sync-id: acd5e576cd13a02e77225f3b308232f8331d3b61

Examples/UIExplorer/UIExplorerUnitTests/RCTEventDispatcherTests.m

@@ -30,7 +30,6 @@
 @synthesize viewTag = _viewTag;
 @synthesize eventName = _eventName;
 @synthesize body = _body;
-@synthesize coalescingKey = _coalescingKey;
 
 - (instancetype)initWithViewTag:(NSNumber *)viewTag eventName:(NSString *)eventName body:(NSDictionary<NSString *, id> *)body
 {

React/Base/RCTEventDispatcher.h

@@ -49,7 +49,6 @@ RCT_EXTERN NSString *RCTNormalizeInputEventName(NSString *eventName);
 @property (nonatomic, strong, readonly) NSNumber *viewTag;
 @property (nonatomic, copy, readonly) NSString *eventName;
 @property (nonatomic, copy, readonly) NSDictionary *body;
-@property (nonatomic, assign, readonly) uint16_t coalescingKey;
 
 - (BOOL)canCoalesce;
 - (id<RCTEvent>)coalesceWithEvent:(id<RCTEvent>)newEvent;

React/Base/RCTEventDispatcher.m

@@ -30,9 +30,7 @@ static NSNumber *RCTGetEventID(id<RCTEvent> event)
 {
   return @(
     event.viewTag.intValue |
-    (((uint64_t)event.eventName.hash & 0xFFFF) << 32)  |
-    (((uint64_t)event.coalescingKey) << 48)
-  );
+    (((uint64_t)event.eventName.hash & 0xFFFF) << 32));
 }
 
 @interface RCTEventDispatcher() <RCTFrameUpdateObserver>

React/Views/RCTScrollView.m

@@ -59,11 +59,6 @@ CGFloat const ZINDEX_STICKY_HEADER = 50;
 
 RCT_NOT_IMPLEMENTED(- (instancetype)init)
 
-- (uint16_t)coalescingKey
-{
-  return 0;
-}
-
 - (NSDictionary *)body
 {
   NSDictionary *body = @{