This also removes some tests which we have grouped together into robust_from_*.pass.cpp tests.
Specifically, checking that
- `ranges::dangling` is returned is done in `libcxx/test/std/algorithms/ranges_robust_against_dangling.pass.cpp`
- `std::invoke` is used is done in `libcxx/test/std/algorithms/ranges_robust_against_omitting_invoke.pass.cpp`.
- implicit conversion to bool works is done in `libcxx/test/std/algorithms/ranges_robust_against_nonbool_predicates.pass.cpp`
Checking the comparison order is invalid because the `operator==` isn't symmetric.
Checking what the exact type of `operator==` is, is invalid because comparing the same object has to yield the same results if the objects are not modified.
Reviewed By: ldionne, #libc
Spies: EricWF, libcxx-commits
Differential Revision: https://reviews.llvm.org/D150588
75eb3bd1a4