Add extracted source directory and README navigation

extracted-source/node_modules/get-proto/Object.getPrototypeOf.js

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+'use strict';
+
+var $Object = require('es-object-atoms');
+
+/** @type {import('./Object.getPrototypeOf')} */
+module.exports = $Object.getPrototypeOf || null;

extracted-source/node_modules/get-proto/Reflect.getPrototypeOf.js

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+'use strict';
+
+/** @type {import('./Reflect.getPrototypeOf')} */
+module.exports = (typeof Reflect !== 'undefined' && Reflect.getPrototypeOf) || null;

extracted-source/node_modules/get-proto/index.js

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+'use strict';
+
+var reflectGetProto = require('./Reflect.getPrototypeOf');
+var originalGetProto = require('./Object.getPrototypeOf');
+
+var getDunderProto = require('dunder-proto/get');
+
+/** @type {import('.')} */
+module.exports = reflectGetProto
+	? function getProto(O) {
+		// @ts-expect-error TS can't narrow inside a closure, for some reason
+		return reflectGetProto(O);
+	}
+	: originalGetProto
+		? function getProto(O) {
+			if (!O || (typeof O !== 'object' && typeof O !== 'function')) {
+				throw new TypeError('getProto: not an object');
+			}
+			// @ts-expect-error TS can't narrow inside a closure, for some reason
+			return originalGetProto(O);
+		}
+		: getDunderProto
+			? function getProto(O) {
+				// @ts-expect-error TS can't narrow inside a closure, for some reason
+				return getDunderProto(O);
+			}
+			: null;