Remove remaining need for fork of RN for win32 JS

change/@office-iss-react-native-win32-2019-12-20-11-19-05-win32defork.json

@@ -0,0 +1,8 @@
+{
+  "type": "patch",
+  "comment": "Remove remaining need for fork of RN for win32 JS",
+  "packageName": "@office-iss/react-native-win32",
+  "email": "acoates@microsoft.com",
+  "commit": "b17624cd44d682c73db5ae17a3d10c8bed07c5f8",
+  "date": "2019-12-20T19:19:05.418Z"
+}

change/react-native-windows-2019-12-20-15-20-03-win32defork.json

@@ -0,0 +1,8 @@
+{
+  "type": "prerelease",
+  "comment": "Fix RNTester bundle (#2728)",
+  "packageName": "react-native-windows",
+  "email": "acoates@microsoft.com",
+  "commit": "65167fb5e52f042879d00891e89ed951bdda84bc",
+  "date": "2019-12-20T23:20:03.026Z"
+}

packages/react-native-win32/package.json

@@ -12,10 +12,10 @@
     "lint": "just-scripts eslint",
     "lint:fix": "eslint ./**/*.js ./**/*.ts? --fix",
     "watch": "tsc -w",
-    "bundle": "just-scripts prepareBundle && react-native bundle --platform win32 --entry-file RNTester.js --bundle-output dist/win32/dev/index.win32.bundle --assets-dest dist/win32/dev",
-    "run-win32": "rex-win32 --bundle RNTester.win32 --component RNTesterApp --basePath ./dist/win32/dev",
-    "run-win32-devmain": "rex-win32 --bundle RNTester.win32 --component RNTesterApp --basePath ./dist/win32/dev --useDevMain",
-    "run-win32-dev-web": "rex-win32 --bundle RNTester.win32 --component RNTesterApp --basePath ./dist/win32/dev --useWebDebugger"
+    "bundle": "just-scripts prepareBundle && react-native bundle --platform win32 --entry-file RNTester.js --bundle-output dist/win32/dev/RNTester.bundle --assets-dest dist/win32/dev",
+    "run-win32": "rex-win32 --bundle RNTester --component RNTesterApp --basePath ./dist/win32/dev",
+    "run-win32-devmain": "rex-win32 --bundle RNTester --component RNTesterApp --basePath ./dist/win32/dev --useDevMain",
+    "run-win32-dev-web": "rex-win32 --bundle RNTester --component RNTesterApp --basePath ./dist/win32/dev --useWebDebugger"
   },
   "dependencies": {
     "@babel/runtime": "^7.4.0",

packages/react-native-win32/src/Libraries/Components/TextInput/TextInputState.win32.js

@@ -0,0 +1,101 @@
+/**
+ * Copyright (c) Microsoft Corporation. All rights reserved.
+ *
+ * @format
+ * @flow strict-local
+ */
+
+'use strict';
+
+const Platform = require('../../Utilities/Platform');
+const UIManager = require('../../ReactNative/UIManager');
+
+let currentlyFocusedID: ?number = null;
+const inputs = new Set();
+
+/**
+ * Returns the ID of the currently focused text field, if one exists
+ * If no text field is focused it returns null
+ */
+function currentlyFocusedField(): ?number {
+  return currentlyFocusedID;
+}
+
+/**
+ * @param {number} TextInputID id of the text field to focus
+ * Focuses the specified text field
+ * noop if the text field was already focused
+ */
+function focusTextInput(textFieldID: ?number) {
+  if (currentlyFocusedID !== textFieldID && textFieldID !== null) {
+    currentlyFocusedID = textFieldID;
+    if (Platform.OS === 'ios') {
+      UIManager.focus(textFieldID);
+    } else if (Platform.OS === 'android') {
+      UIManager.dispatchViewManagerCommand(
+        textFieldID,
+        UIManager.getViewManagerConfig('AndroidTextInput').Commands
+          .focusTextInput,
+        null,
+      );
+      // [Win32
+    } else if (Platform.OS === 'win32') {
+      UIManager.dispatchViewManagerCommand(
+        textFieldID,
+        UIManager.RCTView.Commands.focus,
+        null,
+      );
+    }
+    // Win32]
+  }
+}
+
+/**
+ * @param {number} textFieldID id of the text field to unfocus
+ * Unfocuses the specified text field
+ * noop if it wasn't focused
+ */
+function blurTextInput(textFieldID: ?number) {
+  if (currentlyFocusedID === textFieldID && textFieldID !== null) {
+    currentlyFocusedID = null;
+    if (Platform.OS === 'ios') {
+      UIManager.blur(textFieldID);
+    } else if (Platform.OS === 'android') {
+      UIManager.dispatchViewManagerCommand(
+        textFieldID,
+        UIManager.getViewManagerConfig('AndroidTextInput').Commands
+          .blurTextInput,
+        null,
+      );
+      // [Win32
+    } else if (Platform.OS === 'win32') {
+      UIManager.dispatchViewManagerCommand(
+        textFieldID,
+        UIManager.RCTView.Commands.blur,
+        null,
+      );
+    }
+    // Win32]
+  }
+}
+
+function registerInput(textFieldID: number) {
+  inputs.add(textFieldID);
+}
+
+function unregisterInput(textFieldID: number) {
+  inputs.delete(textFieldID);
+}
+
+function isTextInput(textFieldID: number) {
+  return inputs.has(textFieldID);
+}
+
+module.exports = {
+  currentlyFocusedField,
+  focusTextInput,
+  blurTextInput,
+  registerInput,
+  unregisterInput,
+  isTextInput,
+};