Allow overriding inherited properties of Domado objects by assignment.

* ExpandoProxyHandler no longer treats defineProperty of a property
  name which exists somewhere in the prototype chain differently for
  no good reason.
* ExpandoProxyHandler's reimplementation of assignment no longer
  acts according to the "override mistake" (needed for ES5/3).

Fixes <https://code.google.com/p/google-caja/issues/detail?id=1650>.

@r5365

[ihab.awad, 2013-04-22 16:53:47]

lgtm

https://codereview.appspot.com/8649044/diff/1/src/com/google/caja/plugin/doma...
File src/com/google/caja/plugin/domado.js (right):

https://codereview.appspot.com/8649044/diff/1/src/com/google/caja/plugin/doma...
src/com/google/caja/plugin/domado.js:721: // nonwritable data properties.
I'm confused. We need to do "this" or we need to disable "this"? I think you are
saying: We need to disable this code path because ES5/3 behaves that way, and
the resulting state of affairs is consistent with ECMA 262. Is this correct?

[kpreid2, 2013-04-22 17:31:14]

https://codereview.appspot.com/8649044/diff/1/src/com/google/caja/plugin/doma...
File src/com/google/caja/plugin/domado.js (right):

https://codereview.appspot.com/8649044/diff/1/src/com/google/caja/plugin/doma...
src/com/google/caja/plugin/domado.js:721: // nonwritable data properties.
On 2013/04/22 16:53:47, ihab.awad wrote:
> I'm confused. We need to do "this" or we need to disable "this"?

I am explaining why the following code is commented out.

> I think you are saying: We need to disable this code path because ES5/3
> behaves that way,

Yes.

> and the resulting state of affairs is consistent with ECMA 262. Is this
> correct?

No, the resulting state of affairs is consistent with ES5/3's deliberate
violation of ECMA-262.

On SES, as opposed to ES5/3, this makes no difference because the case never
arises (we avoid giving prototypes non-writable data properties).

[kpreid2, 2013-04-22 17:46:30]

* ExpandoProxyHandler no longer treats defineProperty of a property
  name which exists somewhere in the prototype chain differently for
  no good reason.
* ExpandoProxyHandler's reimplementation of assignment no longer
  acts according to the "override mistake" (needed for ES5/3).

Fixes <https://code.google.com/p/google-caja/issues/detail?id=1650>.

[kpreid2, 2013-04-22 17:47:16]

https://codereview.appspot.com/8649044/diff/1/src/com/google/caja/plugin/doma...
File src/com/google/caja/plugin/domado.js (right):

https://codereview.appspot.com/8649044/diff/1/src/com/google/caja/plugin/doma...
src/com/google/caja/plugin/domado.js:721: // nonwritable data properties.
Have rewritten this comment.