-observeValueForKeyPath now takes nullable parameters in new SDKs.
Fortunately, the test changes should still work with older SDKs because
we can override a T with a T?.
Swift SVN r27532
This takes all %target-run-simple-swift and %target-run-stdlib-swift
invocations and runs them using the interpreter instead. To enable this
mode, pass --param=interpret to lit.py; you can add this flag to the
LLVM_LIT_ARGS CMake setting (which defaults to "-sv").
This doesn't support separated %target-build / %target-run steps, nor
does it work with StdlibUnittest (which uses posix_spawn to run its
subtasks). But it's a start.
<rdar://problem/17938202>
Swift SVN r21391
