TryTruncateFloat32ToUint64 converts a float32 to a uint64. Additionally it
provides an optional second return value which indicates whether the conversion
succeeded (i.e. float32 value was within uint64 range) or not.

I implemented the new operator on x64, arm64, and mips64. @v8-ppc-ports, can you
please take care of the ppc64 implementation of the second output?

Additionally I fixed a bug on x64 and mips64 in the implementation of
TryTruncateFloat64ToUint64. Cases where the input value was between -1 and 0
were handled incorrectly.

R=titzer@chromium.org, v8-arm-ports@googlegroups.com, v8-mips-ports@googlegroups.com

Review URL: https://codereview.chromium.org/1512023002

Cr-Commit-Position: refs/heads/master@{#32796}