FastMathFlags were moved to a separate header to make it possible
to use in IR/Constants.h, which otherwise created circular dependency
between IR/Constants.h and IR/Operator.h.
Update test and also one get() invocation, which was changed by mistake (it called itself after this change).
No. Initially I wanted to check only for presence of floating-point instructions, but then added arguments as was requested, now changed to check everything.