*) For all tests the input validation was incorrect, i.e. some values
were considered invalid although they were valid. The problem was that
values which are outside int range can get in range through truncation.

*) Removed an assertion in the x64 code generation of
TruncateFloat64ToUint32 which trapped on negative inputs.

*) Introduced a new TF operator TruncateFloat32ToUint32 which does
the same as ChangeFloat32ToUint32 but does not trap on negative inputs.

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/1843983002

Cr-Commit-Position: refs/heads/master@{#35176}