Fix garbage collection of unused maps. Null descriptors, created...

Fix garbage collection of unused maps.  Null descriptors, created
by map collection, are now handled correctly everywhere.  The 
map-collect flag is now true by default.

Committed: http://code.google.com/p/v8/source/detail?r=1459

[William Hesse, 2009-03-06 12:18:08]

Null descriptors are no longer returned from searching a DescriptorArray, and
are handled correctly by all users of DescriptorReaders.  This fixes the bug in
garbage collection of maps found in the Presently, Writely, and Trix tests.  Map
collection is reenabled.  Tested on the Presently and Trix tests, and on all our
tests.

[Mads Ager (chromium), 2009-03-06 12:25:28]

LGTM

http://codereview.chromium.org/40218/diff/1/6
File src/factory.cc (left):

http://codereview.chromium.org/40218/diff/1/6#oldcode18
Line 18: // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR
Whoops?

http://codereview.chromium.org/40218/diff/1/3
File src/objects.cc (right):

http://codereview.chromium.org/40218/diff/1/3#newcode5653
Line 5653: details.type() != NULL_DESCRIPTOR &&
I guess you can use !r.IsNullDescriptor() here?

[Kasper Lund, 2009-03-06 12:29:13]

http://codereview.chromium.org/40218/diff/1/6
File src/factory.cc (right):

http://codereview.chromium.org/40218/diff/1/6#newcode539
Line 539: w.WriteFrom(&r);
Weird indentation.

[William Hesse, 2009-03-09 13:31:59]

Addressed comments, added regression test.  The regression test takes 30 seconds
in debug mode, but cannot be made much faster - a mark-sweep garbage collection
is required.

http://codereview.chromium.org/40218/diff/1/6
File src/factory.cc (left):

http://codereview.chromium.org/40218/diff/1/6#oldcode18
Line 18: // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR
On 2009/03/06 12:25:28, Mads Ager wrote:
> Whoops?

Done.

http://codereview.chromium.org/40218/diff/1/6
File src/factory.cc (right):

http://codereview.chromium.org/40218/diff/1/6#newcode539
Line 539: w.WriteFrom(&r);
On 2009/03/06 12:29:13, Kasper Lund wrote:
> Weird indentation.

Done.

http://codereview.chromium.org/40218/diff/1/3
File src/objects.cc (right):

http://codereview.chromium.org/40218/diff/1/3#newcode5653
Line 5653: details.type() != NULL_DESCRIPTOR &&
On 2009/03/06 12:25:28, Mads Ager wrote:
> I guess you can use !r.IsNullDescriptor() here?
Replaced by IsProperty()

[Mads Ager (chromium), 2009-03-09 16:06:52]

LGTM

http://codereview.chromium.org/40218/diff/1006/24
File src/handles.cc (right):

http://codereview.chromium.org/40218/diff/1006/24#newcode470
Line 470: if (!r.IsTransition() && !r.IsNullDescriptor() && !r.IsDontEnum()) {
Can parts of this be replaced by the new IsProperty?

[William Hesse, 2009-03-09 16:23:24]

Ready to commit.

http://codereview.chromium.org/40218/diff/1006/24
File src/handles.cc (right):

http://codereview.chromium.org/40218/diff/1006/24#newcode470
Line 470: if (!r.IsTransition() && !r.IsNullDescriptor() && !r.IsDontEnum()) {
On 2009/03/09 16:06:53, Mads Ager wrote:
> Can parts of this be replaced by the new IsProperty?

Done.