This removes an optimization from the code generator that tries to
materialize certain constants (i.e. context and closure) from the
stackframe when possible. This does not work with Harmony tail calls
which are split into several instructions. There have already been
numerous bugs in this optimization, it is too fragile in its current
form.

R=bmeurer@chromium.org
TEST=mjsunit/regress/regress-crbug-648539
BUG=chromium:648539

Review-Url: https://codereview.chromium.org/2357583003
Cr-Commit-Position: refs/heads/master@{#39583}