Revert "Updated test cases for contextual conversion"

This reverts commit r184100.

It was faling on some bots:
http://bb.pgr.jp/builders/cmake-clang-i686-mingw32/builds/1973/steps/test_clang/logs/Clang%20%3A%3A%20SemaCXX__cxx1y-contextual-conversion-tweaks.cpp