Port 6470ddad

On MIPS different signaling NaN values must be used for hardware and simulator targets, even at snapshot generation when always simulator is used.

Original commit message:
This introduces SilenceNaN operator, which makes sure that we only
store quiet NaNs into holey arrays. We omit the NaN silencing code
at instruction selection time if the input is an operation that
cannot possibly produce signalling NaNs.

BUG=

Review-Url: https://codereview.chromium.org/2171303002
Cr-Commit-Position: refs/heads/master@{#38030}