add types for escape and unescape methods microsoft#18813

although the issue is marked working as expected, it is important to mention that most major browsers maintain support for escape and unescape, and some javascript codebases moving to typescript may have escape and unescape in them. They are valid JavaScript, and thus they should be included in the global definition.

Author: wbhob

src/lib/es5.d.ts

@@ -62,6 +62,18 @@ declare function encodeURI(uri: string): string;
   */
 declare function encodeURIComponent(uriComponent: string): string;
 
+/**
+  * Computes a new string in which certain characters have been replaced by a hexadecimal escape sequence.
+  * @param string A string value
+  */
+declare function escape(string: string): string;
+
+/**
+  * Computes a new string in which hexadecimal escape sequences are replaced with the character that it represents.
+  * @param string A string value
+  */
+declare function unescape(string: string): string;
+
 interface PropertyDescriptor {
     configurable?: boolean;
     enumerable?: boolean;