The FloatMathPlugin provided cross-platform bit-identical floating point, needed for applications such as OpenCroquet/Qwaq/terf. The plugin depends on Sun's fdlibm which is effectively obsolete. There are better solutions; see for an overview http://christian-seiler.de/projekte/fpmath/ and for a solution (provided this is lesser GPL, which a cursory reading suggests it is) https://www.mpfr.org
If taking this approach, instead of needing a FloatMathPlugin we could perhaps arrange that the VM provides cross-platform bit-identical floating point by default, or that the VM is compilable with some flags that result in a VM whose floating point primitives are cross-platform bit-identical. Then one wouldn't have to use an interface to the plugin, with all the headaches that providing support for SmallFloat64 now in introduces, along with the slowness of that plugin interface.