Added macros OBJECT_IMPLEMENTATION and FINAL_OBJECT_IMPLEMENTATION

Added macros OBJECT_IMPLEMENTATION and FINAL_OBJECT_IMPLEMENTATION
which have different implementations of 'operator=' and 'operator^='.
In the case of FINAL_OBJECT_IMPLEMENTATION we do not do the vtable setting
in these methods (Note the |= operator functionality is now subsumed into
the new implementation of "operator^=")
Committed: https://code.google.com/p/dart/source/detail?r=17491

[Ivan Posva, 2013-01-23 03:44:20]

LGTM!

Based on the number of places where the |= crept in this was a needed cleanup.

-Ivan

https://codereview.chromium.org/12052033/diff/9002/vm/object.h
File vm/object.h (right):

https://codereview.chromium.org/12052033/diff/9002/vm/object.h#newcode118
vm/object.h:118: object() : super() {}                                          
             \
Can't we prevent subclassing of FINAL classes by marking their constructors
private?

[siva, 2013-01-23 19:26:53]

https://chromiumcodereview.appspot.com/12052033/diff/9002/vm/object.h
File vm/object.h (right):

https://chromiumcodereview.appspot.com/12052033/diff/9002/vm/object.h#newcode118
vm/object.h:118: object() : super() {}                                          
             \
On 2013/01/23 03:44:20, Ivan Posva wrote:
> Can't we prevent subclassing of FINAL classes by marking their constructors
> private?

Done.

[srdjan, 2013-01-23 19:45:37]

lgtm