Formatter: Refactor the cast detection code to be a bit more readable.

No functionality change. Also add another cast test.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175029 91177308-0d34-0410-b5e6-96231b3b80d8
Formatter: Add more cast tests.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175030 91177308-0d34-0410-b5e6-96231b3b80d8
Formatter: And more cast tests (these don't pass yet).



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175031 91177308-0d34-0410-b5e6-96231b3b80d8