[clang] [WebKit Checkers] Trace through temporaries in tryToFindPtrOrigin (PR #224877)

[via cfe-commits]

geoffreygaren wrote:

Updated patch passes `CrossedShortLivedTemporary` as an argument to the callback rather than treating it as an out parameter. Because `CrossedShortLivedTemporary` should propagate, `tryToFindPtrOrigin` now has an internal `Impl` to handle initializing the value of `CrossedShortLivedTemporary` before recursion starts.

https://github.com/llvm/llvm-project/pull/224877