A64: Remove Assembler::finalized_ flag and logic

A64: Remove Assembler::finalized_ flag and logic

The flag is supposed to check that the assembled code was used. However,
codegen uses masm::CodeObject() to retrieve the code which is not
detected by this logic. We could make CodeObject() set finalized_ as
wel, however, it's used all over the place which would make the flag
worthless.

BUG=none
R=rodolph.perfetta@arm.com, ulan@chromium.org
LOG=n

Committed: https://code.google.com/p/v8/source/detail?r=19261

[Rodolph Perfetta (ARM), 2014-02-11 09:17:01]

lgtm

[jochen (gone - plz use gerrit), 2014-02-11 09:25:13]

Committed patchset #1 manually as r19261 (presubmit successful).