A64: Indicate the correct size for constant pools.

A64: Indicate the correct size for constant pools.

This fixes potential issues that would appear when trying to insert a breakpoint
from JavaScript.
Without this, computing the mapping of addresses between versions of the code with
and without debug slots could be off by an instruction, trigerring nasty bugs.

R=jochen@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=19350

[jochen (gone - plz use gerrit), 2014-02-13 09:22:01]

lgtm

[Alexandre Rames, 2014-02-13 10:27:50]

Committed patchset #1 manually as r19350 (presubmit successful).