Back out "Align multi-line TextInput onSubmitEditing behavior"

Summary:
This is a revert of D22488870 (facebook@521b167). (facebook#29177)
We have to revert it because we realized that it's a breaking change without a very good reason. We have to figure out a better way to unify platform behaviors.

Changelog:
[iOS][Fixed] - Reverted recent change in TextInput (facebook#29177)

Reviewed By: fkgozali

Differential Revision: D24200517

fbshipit-source-id: af0e561a6b8d9ade487be6b197a5d79d326442b6

Libraries/Text/TextInput/RCTBaseTextInputView.m

@@ -413,13 +413,11 @@ - (BOOL)textInputShouldReturn
   // `onSubmitEditing` is called when "Submit" button
   // (the blue key on onscreen keyboard) did pressed
   // (no connection to any specific "submitting" process).
-  if (_blurOnSubmit) {
-    [_eventDispatcher sendTextEventWithType:RCTTextEventTypeSubmit
-                                   reactTag:self.reactTag
-                                       text:[self.backedTextInputView.attributedText.string copy]
-                                        key:nil
-                                 eventCount:_nativeEventCount];
-  }
+  [_eventDispatcher sendTextEventWithType:RCTTextEventTypeSubmit
+                                 reactTag:self.reactTag
+                                     text:[self.backedTextInputView.attributedText.string copy]
+                                      key:nil
+                               eventCount:_nativeEventCount];
 
   return _blurOnSubmit;
 }