This fixes the lifetime of nodes created by JSGlobalSpecialization that
contain a simplified operator. In the case where this reducer runs as
part of the inliner, the SimplifiedOperatorBuilder was instantiated with
the wrong zone. This led to use-after-free of simplified operators.

To avoid such situations in the future, we decided to move this operator
builder into the JSGraph and make the situation uniform with all other
operator builders.

R=bmeurer@chromium.org
BUG=chromium:543528
LOG=n

Review URL: https://codereview.chromium.org/1409993002

Cr-Commit-Position: refs/heads/master@{#31334}