Use new defaultRealTolerance() to stabilise some tests

Use new defaultRealTolerance() to stabilise some tests

The single-precision values in these tests sometimes failed to compare
equal with string-ified versions when the test was run from a
double-precision build on Windows. That difference may have originated
in how a rounding mode was implemented in different libraries, but
ultimately doesn't matter because the value should not be compared as
if it was computed in double precision.

Change-Id: I9b7c2b9409145cc579229f0866935754e3a9dcac