Import dispatchCommand utility from the right Renderer module

Summary:
With the new architecture, this module should be using the implementation from ReactFabric instead. However, given the ReactNative module had side effects (like registering `RCTEventEmitter`), let's import from ReactFabric only in the latest "new architecture" mode.

Changelog: [Internal]

Reviewed By: TheSavior

Differential Revision: D36535626

fbshipit-source-id: 6758b671df9a47607d8caf4a021ac73410f4c6e9

Libraries/Utilities/codegenNativeCommands.js

@@ -8,7 +8,16 @@
  * @flow
  */
 
-import {dispatchCommand} from '../../Libraries/Renderer/shims/ReactNative';
+let dispatchCommand;
+if (global.RN$Bridgeless) {
+  // Note: this function has the same implementation in the legacy and new renderer.
+  // However, evaluating the old renderer comes with some side effects.
+  dispatchCommand =
+    require('../../Libraries/Renderer/shims/ReactFabric').dispatchCommand;
+} else {
+  dispatchCommand =
+    require('../../Libraries/Renderer/shims/ReactNative').dispatchCommand;
+}
 
 type Options<T = string> = $ReadOnly<{|
   supportedCommands: $ReadOnlyArray<T>,