Provide baseline for experimental GC implementation.

Provide baseline for experimental GC implementation.

(Third attempt).

- Remove anything related to mark-compact collection;
- Guard current write-barrier implementation with ENABLE_CARDMARKING_WRITE_BARRIER on all platforms to disable. Conditional compilation was used instead of flag to detect all places where we emit write-barrier. Some of them depend on actuall instructions sequence used inside write-barrier.

Committed: http://code.google.com/p/v8/source/detail?r=6019

[Erik Corry, 2010-12-14 21:05:26]

LGTM

Should be easy to find all the places where we have write barrier code now.  I'm
surprised at how many places that is.

http://codereview.chromium.org/5736008/diff/1/src/arm/full-codegen-arm.cc
File src/arm/full-codegen-arm.cc (right):

http://codereview.chromium.org/5736008/diff/1/src/arm/full-codegen-arm.cc#new...
src/arm/full-codegen-arm.cc:640: int offset =
Context::SlotOffset(slot->index());
Seems like this ifdef and about 10 others could have been avoided if we had just
put the ifdef in RecordWrite.  Also there's nothing CARDMARKING about this code.
 Any other write barrier that uses the same number of registers could be called
here.

http://codereview.chromium.org/5736008/diff/1/src/globals.h
File src/globals.h (right):

http://codereview.chromium.org/5736008/diff/1/src/globals.h#newcode30
src/globals.h:30: 
Inadvertent edit