Add NumberAbs operator to implement an inline version of Math.abs, that
can be optimized and eliminated. We don't use any speculation here, but
for now stick to the information we can infer (this way we avoid the
inherent deopt loops that Crankshaft has around Math.abs).

CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
R=jarin@chromium.org
BUG=v8:5086

Review-Url: https://codereview.chromium.org/2096403002
Cr-Commit-Position: refs/heads/master@{#37306}