fix typo in type definition (#11346)

Author: Michael

src/lib/es2015.core.d.ts

@@ -201,7 +201,7 @@ interface NumberConstructor {
 
     /**
       * Returns true if passed value is finite.
-      * Unlike the global isFininte, Number.isFinite doesn't forcibly convert the parameter to a
+      * Unlike the global isFinite, Number.isFinite doesn't forcibly convert the parameter to a
       * number. Only finite values of the type number, result in true.
       * @param number A numeric value.
       */