Change Omit back to using Pick<T, Exclude<keyof T, K>> in order to maintain modifiers.

src/lib/es5.d.ts

@@ -1446,9 +1446,7 @@ type Extract<T, U> = T extends U ? T : never;
 /**
  * Construct a type with the properties of T except for those in type K.
  */
-type Omit<T, K extends keyof any> = {
-    [P in Exclude<keyof T, K>]: T[P]
-};
+type Omit<T, K extends keyof any> = Pick<T, Exclude<keyof T, K>>;
 
 /**
  * Exclude null and undefined from T