Allow live reload even on errors.

Summary:
Live reload is disabled when an error has occurred. This requires the developer to fix the error and then switch to the simulator to reload the device manually; impacting developer flow and increasing alt tabbing. This pull request fixes that by allowing live reload to work even on errors.

This fixes issue: #1343.
Closes https://github.com/facebook/react-native/pull/1549
Github Author: Ruben Niculcea <ruben.niculcea@gmail.com>

Test Plan: Imported from GitHub, without a `Test Plan:` line.

React/Base/RCTBridge.m

@@ -995,6 +995,8 @@ RCT_INNER_BRIDGE_ONLY(_invokeAndProcessModule:(__unused NSString *)module
         return;
       }
 
+      [[RCTRedBox sharedInstance] dismiss];
+
       RCTSourceCode *sourceCodeModule = self.modules[RCTBridgeModuleNameForClass([RCTSourceCode class])];
       sourceCodeModule.scriptURL = bundleURL;
       sourceCodeModule.scriptText = script;

React/Base/RCTDevMenu.m

@@ -119,6 +119,11 @@ RCT_EXPORT_MODULE()
                                name:RCTJavaScriptDidLoadNotification
                              object:nil];
 
+    [notificationCenter addObserver:self
+                           selector:@selector(jsLoaded:)
+                               name:RCTJavaScriptDidFailToLoadNotification
+                             object:nil];
+
     _defaults = [NSUserDefaults standardUserDefaults];
     _settings = [[NSMutableDictionary alloc] init];
     _extraMenuItems = [NSMutableArray array];