Don't bundle ReactComponentTreeHook in production (#7653)

Fixes #7492.
This was a build size regression introduced in #7164.

Author: gaearon

src/umd/ReactUMDEntry.js

@@ -17,8 +17,17 @@ var React = require('React');
 var ReactUMDEntry = Object.assign({
   __SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: {
     ReactCurrentOwner: require('ReactCurrentOwner'),
-    ReactComponentTreeHook: require('ReactComponentTreeHook'),
   },
 }, React);
 
+if (__DEV__) {
+  Object.assign(
+    ReactUMDEntry.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED,
+    {
+      // ReactComponentTreeHook should not be included in production.
+      ReactComponentTreeHook: require('ReactComponentTreeHook'),
+    }
+  );
+}
+
 module.exports = ReactUMDEntry;

src/umd/ReactWithAddonsUMDEntry.js

@@ -17,8 +17,17 @@ var ReactWithAddons = require('ReactWithAddons');
 var ReactWithAddonsUMDEntry = Object.assign({
   __SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: {
     ReactCurrentOwner: require('ReactCurrentOwner'),
-    ReactComponentTreeHook: require('ReactComponentTreeHook'),
   },
 }, ReactWithAddons);
 
+if (__DEV__) {
+  Object.assign(
+    ReactWithAddonsUMDEntry.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED,
+    {
+      // ReactComponentTreeHook should not be included in production.
+      ReactComponentTreeHook: require('ReactComponentTreeHook'),
+    }
+  );
+}
+
 module.exports = ReactWithAddonsUMDEntry;