Remove core-js guard.

_baseIsNative.js

@@ -1,48 +0,0 @@
-import isFunction from './isFunction.js';
-import isMasked from './_isMasked.js';
-import isObject from './isObject.js';
-import toSource from './_toSource.js';
-
-/**
- * Used to match `RegExp`
- * [syntax characters](http://ecma-international.org/ecma-262/7.0/#sec-patterns).
- */
-const reRegExpChar = /[\\^$.*+?()[\]{}|]/g;
-
-/** Used to detect host constructors (Safari). */
-const reIsHostCtor = /^\[object .+?Constructor\]$/;
-
-/** Used for built-in method references. */
-const funcProto = Function.prototype;
-const objectProto = Object.prototype;
-
-/** Used to resolve the decompiled source of functions. */
-const funcToString = funcProto.toString;
-
-/** Used to check objects for own properties. */
-const hasOwnProperty = objectProto.hasOwnProperty;
-
-/** Used to detect if a method is native. */
-const reIsNative = RegExp(`^${
-  funcToString.call(hasOwnProperty)
-    .replace(reRegExpChar, '\\$&')
-    .replace(/hasOwnProperty|(function).*?(?=\\\()| for .+?(?=\\\])/g, '$1.*?')
-}$`);
-
-/**
- * The base implementation of `isNative` without bad shim checks.
- *
- * @private
- * @param {*} value The value to check.
- * @returns {boolean} Returns `true` if `value` is a native function,
- *  else `false`.
- */
-function baseIsNative(value) {
-  if (!isObject(value) || isMasked(value)) {
-    return false;
-  }
-  const pattern = isFunction(value) ? reIsNative : reIsHostCtor;
-  return pattern.test(toSource(value));
-}
-
-export default baseIsNative;

_coreJsData.js

@@ -1,6 +0,0 @@
-import root from './_root.js';
-
-/** Used to detect overreaching core-js shims. */
-const coreJsData = root['__core-js_shared__'];
-
-export default coreJsData;

_getNative.js

@@ -1,5 +1,4 @@
-import baseIsNative from './_baseIsNative.js';
-import getValue from './_getValue.js';
+import isNative from './isNative.js';
 
 /**
  * Gets the native function at `key` of `object`.
@@ -10,8 +9,8 @@ import getValue from './_getValue.js';
  * @returns {*} Returns the function if it's native, else `undefined`.
  */
 function getNative(object, key) {
-  const value = getValue(object, key);
-  return baseIsNative(value) ? value : undefined;
+  const value = object == null ? undefined : object[key];
+  return isNative(value) ? value : undefined;
 }
 
 export default getNative;

_getValue.js

@@ -1,13 +0,0 @@
-/**
- * Gets the value at `key` of `object`.
- *
- * @private
- * @param {Object} [object] The object to query.
- * @param {string} key The key of the property to get.
- * @returns {*} Returns the property value.
- */
-function getValue(object, key) {
-  return object == null ? undefined : object[key];
-}
-
-export default getValue;

_isMaskable.js

@@ -1,14 +0,0 @@
-import coreJsData from './_coreJsData.js';
-import isFunction from './isFunction.js';
-import stubFalse from './stubFalse.js';
-
-/**
- * Checks if `func` is capable of being masked.
- *
- * @private
- * @param {*} value The value to check.
- * @returns {boolean} Returns `true` if `func` is maskable, else `false`.
- */
-const isMaskable = coreJsData ? isFunction : stubFalse;
-
-export default isMaskable;

_isMasked.js

@@ -1,20 +0,0 @@
-import coreJsData from './_coreJsData.js';
-
-/** Used to detect methods masquerading as native. */
-const maskSrcKey = ((() => {
-  const uid = /[^.]+$/.exec(coreJsData && coreJsData.keys && coreJsData.keys.IE_PROTO || '');
-  return uid ? `Symbol(src)_1.${ uid }` : '';
-})());
-
-/**
- * Checks if `func` has its source masked.
- *
- * @private
- * @param {Function} func The function to check.
- * @returns {boolean} Returns `true` if `func` is masked, else `false`.
- */
-function isMasked(func) {
-  return !!maskSrcKey && (maskSrcKey in func);
-}
-
-export default isMasked;

isNative.js

@@ -1,20 +1,36 @@
-import baseIsNative from './_baseIsNative.js';
-import isMaskable from './_isMaskable.js';
+import isFunction from './isFunction.js';
+import isObject from './isObject.js';
+import toSource from './_toSource.js';
 
-/** Error message constants. */
-const CORE_ERROR_TEXT = 'Unsupported core-js use. Try https://npms.io/search?q=ponyfill.';
+/**
+ * Used to match `RegExp`
+ * [syntax characters](http://ecma-international.org/ecma-262/7.0/#sec-patterns).
+ */
+const reRegExpChar = /[\\^$.*+?()[\]{}|]/g;
+
+/** Used to detect host constructors (Safari). */
+const reIsHostCtor = /^\[object .+?Constructor\]$/;
+
+/** Used for built-in method references. */
+const funcProto = Function.prototype;
+const objectProto = Object.prototype;
+
+/** Used to resolve the decompiled source of functions. */
+const funcToString = funcProto.toString;
+
+/** Used to check objects for own properties. */
+const hasOwnProperty = objectProto.hasOwnProperty;
+
+/** Used to detect if a method is native. */
+const reIsNative = RegExp(`^${
+  funcToString.call(hasOwnProperty)
+    .replace(reRegExpChar, '\\$&')
+    .replace(/hasOwnProperty|(function).*?(?=\\\()| for .+?(?=\\\])/g, '$1.*?')
+}$`);
 
 /**
  * Checks if `value` is a pristine native function.
  *
- * **Note:** This method can't reliably detect native functions in the presence
- * of the core-js package because core-js circumvents this kind of detection.
- * Despite multiple requests, the core-js maintainer has made it clear: any
- * attempt to fix the detection will be obstructed. As a result, we're left
- * with little choice but to throw an error. Unfortunately, this also affects
- * packages, like [babel-polyfill](https://www.npmjs.com/package/babel-polyfill),
- * which rely on core-js.
- *
  * @static
  * @since 3.0.0
  * @category Lang
@@ -30,10 +46,11 @@ const CORE_ERROR_TEXT = 'Unsupported core-js use. Try https://npms.io/search?q=p
  * // => false
  */
 function isNative(value) {
-  if (isMaskable(value)) {
-    throw new Error(CORE_ERROR_TEXT);
+  if (!isObject(value)) {
+    return false;
   }
-  return baseIsNative(value);
+  const pattern = isFunction(value) ? reIsNative : reIsHostCtor;
+  return pattern.test(toSource(value));
 }
 
 export default isNative;