Avoid meta programming to initialize functions in module scope (#26388)

I'm trying to get rid of all meta programming in the module scope so
that closure can do a better job figuring out cyclic dependencies and
ability to reorder.

This is converting a lot of the patterns that assign functions
conditionally to using function declarations instead.

```
let fn;
if (__DEV__) {
  fn = function() {
    ...
  };
}
```
->
```
function fn() {
  if (__DEV__) {
    ...
  }
}
```

packages/dom-event-testing-library/domEnvironment.js

@@ -13,7 +13,7 @@
  * Change environment support for PointerEvent.
  */
 
-const emptyFunction = function () {};
+function emptyFunction() {}
 
 export function hasPointerEvent() {
  return global != null && global.PointerEvent != null;

packages/react-dom-bindings/src/client/ReactDOMComponent.js

@@ -94,15 +94,8 @@ const HTML = '__html';
 let warnedUnknownTags: {
  [key: string]: boolean,
 };
-
-let validatePropertiesInDevelopment;
-let warnForPropDifference;
-let warnForExtraAttributes;
-let warnForInvalidEventListener;
 let canDiffStyleForHydrationWarning;
 
-let normalizeHTML;
-
 if (__DEV__) {
  warnedUnknownTags = {
  // There are working polyfills for <dialog>. Let people use it.
@@ -115,15 +108,6 @@ if (__DEV__) {
  webview: true,
  };
 
- validatePropertiesInDevelopment = function (type: string, props: any) {
- validateARIAProperties(type, props);
- validateInputProperties(type, props);
- validateUnknownProperties(type, props, {
- registrationNameDependencies,
- possibleRegistrationNames,
- });
- };
-
  // IE 11 parses & normalizes the style attribute as opposed to other
  // browsers. It adds spaces and sorts the properties in some
  // non-alphabetical order. Handling that would require sorting CSS
@@ -133,12 +117,25 @@ if (__DEV__) {
  // in that browser completely in favor of doing all that work.
  // See https://github.com/facebook/react/issues/11807
  canDiffStyleForHydrationWarning = canUseDOM && !document.documentMode;
+}
 
- warnForPropDifference = function (
- propName: string,
- serverValue: mixed,
- clientValue: mixed,
- ) {
+function validatePropertiesInDevelopment(type: string, props: any) {
+ if (__DEV__) {
+ validateARIAProperties(type, props);
+ validateInputProperties(type, props);
+ validateUnknownProperties(type, props, {
+ registrationNameDependencies,
+ possibleRegistrationNames,
+ });
+ }
+}
+
+function warnForPropDifference(
+ propName: string,
+ serverValue: mixed,
+ clientValue: mixed,
+) {
+ if (__DEV__) {
  if (didWarnInvalidHydration) {
  return;
  }
@@ -156,9 +153,11 @@ if (__DEV__) {
  JSON.stringify(normalizedServerValue),
  JSON.stringify(normalizedClientValue),
  );
- };
+ }
+}
 
- warnForExtraAttributes = function (attributeNames: Set<string>) {
+function warnForExtraAttributes(attributeNames: Set<string>) {
+ if (__DEV__) {
  if (didWarnInvalidHydration) {
  return;
  }
@@ -168,12 +167,11 @@ if (__DEV__) {
  names.push(name);
  });
  console.error('Extra attributes from the server: %s', names);
- };
+ }
+}
 
- warnForInvalidEventListener = function (
- registrationName: string,
- listener: any,
- ) {
+function warnForInvalidEventListener(registrationName: string, listener: any) {
+ if (__DEV__) {
  if (listener === false) {
  console.error(
  'Expected `%s` listener to be a function, instead got `false`.\n\n' +
@@ -190,11 +188,13 @@ if (__DEV__) {
  typeof listener,
  );
  }
- };
+ }
+}
 
- // Parse the HTML and read it back to normalize the HTML string so that it
- // can be used for comparison.
- normalizeHTML = function (parent: Element, html: string) {
+// Parse the HTML and read it back to normalize the HTML string so that it
+// can be used for comparison.
+function normalizeHTML(parent: Element, html: string) {
+ if (__DEV__) {
  // We could have created a separate document here to avoid
  // re-initializing custom elements if they exist. But this breaks
  // how <noscript> is being handled. So we use the same document.
@@ -208,7 +208,7 @@ if (__DEV__) {
  );
  testElement.innerHTML = html;
  return testElement.innerHTML;
- };
+ }
 }
 
 // HTML parsing normalizes CR and CRLF to LF.

packages/react-dom-bindings/src/client/setInnerHTML.js

@@ -7,24 +7,15 @@
  * @flow
  */
 
+/* globals MSApp */
+
 import {SVG_NAMESPACE} from './DOMNamespaces';
-import createMicrosoftUnsafeLocalFunction from './createMicrosoftUnsafeLocalFunction';
 import {enableTrustedTypesIntegration} from 'shared/ReactFeatureFlags';
 
 // SVG temp container for IE lacking innerHTML
 let reusableSVGContainer: HTMLElement;
 
-/**
- * Set the innerHTML property of a node
- *
- * @param {DOMElement} node
- * @param {string} html
- * @internal
- */
-const setInnerHTML: (
- node: Element,
- html: {valueOf(): {toString(): string, ...}, ...},
-) => void = createMicrosoftUnsafeLocalFunction(function (
+function setInnerHTMLImpl(
  node: Element,
  html: {valueOf(): {toString(): string, ...}, ...},
 ): void {
@@ -66,6 +57,26 @@ const setInnerHTML: (
  }
  }
  node.innerHTML = (html: any);
-});
+}
+
+let setInnerHTML: (
+ node: Element,
+ html: {valueOf(): {toString(): string, ...}, ...},
+) => void = setInnerHTMLImpl;
+// $FlowFixMe[cannot-resolve-name]
+if (typeof MSApp !== 'undefined' && MSApp.execUnsafeLocalFunction) {
+ /**
+ * Create a function which has 'unsafe' privileges (required by windows8 apps)
+ */
+ setInnerHTML = function (
+ node: Element,
+ html: {valueOf(): {toString(): string, ...}, ...},
+ ): void {
+ // $FlowFixMe[cannot-resolve-name]
+ return MSApp.execUnsafeLocalFunction(function () {
+ return setInnerHTMLImpl(node, html);
+ });
+ };
+}
 
 export default setInnerHTML;

packages/react-dom-bindings/src/client/setTextContent.js

@@ -18,7 +18,7 @@ import {TEXT_NODE} from './HTMLNodeType';
  * @param {string} text
  * @internal
  */
-const setTextContent = function (node: Element, text: string): void {
+function setTextContent(node: Element, text: string): void {
  if (text) {
  const firstChild = node.firstChild;
 
@@ -32,6 +32,6 @@ const setTextContent = function (node: Element, text: string): void {
  }
  }
  node.textContent = text;
-};
+}
 
 export default setTextContent;