[test] a self-contained version of rdar36838495
Adds a self-contained version of the validation test rdar36838495.swift
Generalizing the `filter(_:)` functions to typed throws slows down the type checker, changing the performance of this test. It’s not completely clear to me whether the test guards a regression of the type checker or of the standard library, so this adds a reproduction of the test’s original form and performance.
