fix(lib/es2015): Fix types of Reflect methods (#41987)

src/lib/es2015.reflect.d.ts

@@ -1,15 +1,103 @@
 declare namespace Reflect {
+    /**
+     * Calls the function with the specified object as the this value
+     * and the elements of specified array as the arguments.
+     * @param target The function to call.
+     * @param thisArgument The object to be used as the this object.
+     * @param argumentsList An array of argument values to be passed to the function.
+     */
     function apply(target: Function, thisArgument: any, argumentsList: ArrayLike<any>): any;
-    function construct(target: Function, argumentsList: ArrayLike<any>, newTarget?: any): any;
+
+    /**
+     * Constructs the target with the elements of specified array as the arguments
+     * and the specified constructor as the `new.target` value.
+     * @param target The constructor to invoke.
+     * @param argumentsList An array of argument values to be passed to the constructor.
+     * @param newTarget The constructor to be used as the `new.target` object.
+     */
+    function construct(target: Function, argumentsList: ArrayLike<any>, newTarget?: Function): any;
+
+    /**
+     * Adds a property to an object, or modifies attributes of an existing property.
+     * @param target Object on which to add or modify the property. This can be a native JavaScript object
+     *        (that is, a user-defined object or a built in object) or a DOM object.
+     * @param propertyKey The property name.
+     * @param attributes Descriptor for the property. It can be for a data property or an accessor property.
+     */
     function defineProperty(target: object, propertyKey: PropertyKey, attributes: PropertyDescriptor): boolean;
+
+    /**
+     * Removes a property from an object, equivalent to `delete target[propertyKey]`,
+     * except it won't throw if `target[propertyKey]` is non-configurable.
+     * @param target Object from which to remove the own property.
+     * @param propertyKey The property name.
+     */
     function deleteProperty(target: object, propertyKey: PropertyKey): boolean;
+
+    /**
+     * Gets the property of target, equivalent to `target[propertyKey]` when `receiver === target`.
+     * @param target Object that contains the property on itself or in its prototype chain.
+     * @param propertyKey The property name.
+     * @param receiver The reference to use as the `this` value in the getter function,
+     *        if `target[propertyKey]` is an accessor property.
+     */
     function get(target: object, propertyKey: PropertyKey, receiver?: any): any;
+
+    /**
+     * Gets the own property descriptor of the specified object.
+     * An own property descriptor is one that is defined directly on the object and is not inherited from the object's prototype.
+     * @param target Object that contains the property.
+     * @param propertyKey The property name.
+     */
     function getOwnPropertyDescriptor(target: object, propertyKey: PropertyKey): PropertyDescriptor | undefined;
-    function getPrototypeOf(target: object): object;
+
+    /**
+     * Returns the prototype of an object.
+     * @param target The object that references the prototype.
+     */
+    function getPrototypeOf(target: object): object | null;
+
+    /**
+     * Equivalent to `propertyKey in target`.
+     * @param target Object that contains the property on itself or in its prototype chain.
+     * @param propertyKey Name of the property.
+     */
     function has(target: object, propertyKey: PropertyKey): boolean;
+
+    /**
+     * Returns a value that indicates whether new properties can be added to an object.
+     * @param target Object to test.
+     */
     function isExtensible(target: object): boolean;
-    function ownKeys(target: object): PropertyKey[];
+
+    /**
+     * Returns the string and symbol keys of the own properties of an object. The own properties of an object
+     * are those that are defined directly on that object, and are not inherited from the object's prototype.
+     * @param target Object that contains the own properties.
+     */
+    function ownKeys(target: object): (string | symbol)[];
+
+    /**
+     * Prevents the addition of new properties to an object.
+     * @param target Object to make non-extensible.
+     * @return Whether the object has been made non-extensible.
+     */
     function preventExtensions(target: object): boolean;
+
+    /**
+     * Sets the property of target, equivalent to `target[propertyKey] = value` when `receiver === target`.
+     * @param target Object that contains the property on itself or in its prototype chain.
+     * @param propertyKey Name of the property.
+     * @param receiver The reference to use as the `this` value in the setter function,
+     *        if `target[propertyKey]` is an accessor property.
+     */
     function set(target: object, propertyKey: PropertyKey, value: any, receiver?: any): boolean;
-    function setPrototypeOf(target: object, proto: any): boolean;
+
+    /**
+     * Sets the prototype of a specified object o to object proto or null.
+     * @param target The object to change its prototype.
+     * @param proto The value of the new prototype or null.
+     * @return Whether setting the prototype was successful.
+     */
+    function setPrototypeOf(target: object, proto: object | null): boolean;
 }

tests/baselines/reference/modularizeLibrary_UsingES5LibAndES6FeatureLibs.types

@@ -16,10 +16,10 @@ var p = new Proxy(t, {});
 >{} : {}
 
 Reflect.ownKeys({});
->Reflect.ownKeys({}) : (string | number | symbol)[]
->Reflect.ownKeys : (target: object) => (string | number | symbol)[]
+>Reflect.ownKeys({}) : (string | symbol)[]
+>Reflect.ownKeys : (target: object) => (string | symbol)[]
 >Reflect : typeof Reflect
->ownKeys : (target: object) => (string | number | symbol)[]
+>ownKeys : (target: object) => (string | symbol)[]
 >{} : {}
 
 function* idGen() {