Performance measurements show that the position independent code is
usually slightly faster than the position dependent code, and there
seems to be no noticable regression.

This also gets rid of a lot of support code that was only required to allow
embedding labels into the code stream. And it implies that neither the GC
nor the deserializer need to do anything for jump tables.

R=svenpanne@chromium.org
BUG=v8:3872
LOG=n

Review URL: https://codereview.chromium.org/1069633002

Cr-Commit-Position: refs/heads/master@{#27646}