Make sure all new Code objects have a non-null PcDescriptors

Adds an empty PcDescriptors instance to the VM-isolate.
All newly created code objects point to the empty PcDescriptors instance.

R=iposva@google.com

Committed: https://code.google.com/p/dart/source/detail?r=31958

[Ivan Posva, 2014-01-21 06:36:05]

LGTMwC

-Ivan

https://codereview.chromium.org/142233002/diff/1/runtime/vm/object.cc
File runtime/vm/object.cc (right):

https://codereview.chromium.org/142233002/diff/1/runtime/vm/object.cc#newcode658
runtime/vm/object.cc:658: empty_descriptors_->raw()->ptr()->length_ =
Smi::New(0);
Can't you use raw_ptr() instead of raw()->ptr()?
Same above when initializing the empty_array.

https://codereview.chromium.org/142233002/diff/1/runtime/vm/object.h
File runtime/vm/object.h (right):

https://codereview.chromium.org/142233002/diff/1/runtime/vm/object.h#newcode3001
runtime/vm/object.h:3001: friend class Object;
Why was this needed?

[Cutch, 2014-01-21 15:49:58]

https://codereview.chromium.org/142233002/diff/1/runtime/vm/object.cc
File runtime/vm/object.cc (right):

https://codereview.chromium.org/142233002/diff/1/runtime/vm/object.cc#newcode658
runtime/vm/object.cc:658: empty_descriptors_->raw()->ptr()->length_ =
Smi::New(0);
On 2014/01/21 06:36:05, Ivan Posva wrote:
> Can't you use raw_ptr() instead of raw()->ptr()?
> Same above when initializing the empty_array.

Done here and above.

https://codereview.chromium.org/142233002/diff/1/runtime/vm/object.h
File runtime/vm/object.h (right):

https://codereview.chromium.org/142233002/diff/1/runtime/vm/object.h#newcode3001
runtime/vm/object.h:3001: friend class Object;
On 2014/01/21 06:36:05, Ivan Posva wrote:
> Why was this needed?

The call to initializeHandle from Object::InitOnce()

[Cutch, 2014-01-21 16:42:42]

Committed patchset #2 manually as r31958 (presubmit successful).