The return type of 'PointerUnion::is' has been 'int' since it was first
added in March 2009, in SVN r67987, or
The only other change to this member function was a clang-format applied
in December 2015, in SVN r256513, or
However, since the return value is the result of a == comparison, an
implicit cast must be made converting the boolean result to an int.
Change the return type to bool to remove the need for such a cast.
I ran llvm-project check-all under ASAN, no failures were reported
(other than obviously unrelated tests that were already failing in