Don't attempt to load RCTDevLoadingView lazily

Summary:
There's a very old issue with reload logic: invalidation and resetting up of the bridge could be racing. In this case, we hit a redbox when:
* Chrome debugger is enabled in previous app run, then we launch the app again
* The bridge starts, then immediately reloads itself to connect to Chrome
* On the 2nd setup, the logic to update the green loading bar, with the % indicator for loading off metro, failed to find the DevLoadingView module instance because the bridge is in the middle of invalidating

See facebook#23235

To test:
Using react-native init from github, do the steps in facebook#23235, no more redbox. Note that the loading indicator % won't be proper still, but at least it doesn't crash/redbox.

Reviewed By: JoshuaGross

Differential Revision: D14110814

fbshipit-source-id: 835061e50acc6968bffbcc2ddfbe8da79a100df9

Author: fkgozali

React/Base/RCTBridge.m

@@ -287,6 +287,8 @@ - (void)reload
    * Any thread
    */
   dispatch_async(dispatch_get_main_queue(), ^{
+    // WARNING: Invalidation is async, so it may not finish before re-setting up the bridge,
+    // causing some issues. TODO: revisit this post-Fabric/TurboModule.
     [self invalidate];
     [self setUp];
   });

React/CxxBridge/RCTCxxBridge.mm

@@ -357,7 +357,9 @@ - (void)start
     dispatch_group_leave(prepareBridge);
   } onProgress:^(RCTLoadingProgress *progressData) {
 #if RCT_DEV && __has_include("RCTDevLoadingView.h")
-    RCTDevLoadingView *loadingView = [weakSelf moduleForClass:[RCTDevLoadingView class]];
+    // Note: RCTDevLoadingView should have been loaded at this point, so no need to allow lazy loading.
+    RCTDevLoadingView *loadingView = [weakSelf moduleForName:RCTBridgeModuleNameForClass([RCTDevLoadingView class])
+                                       lazilyLoadIfNecessary:NO];
     [loadingView updateProgress:progressData];
 #endif
   }];