Fix getOwnPropertyDescriptor() support for index properties.

Fix getOwnPropertyDescriptor() support for index properties.

Add support for index properties with getters, setters or indexed interceptors.

For indexed interceptor case only fix crashes, do not guarantee any semantic soundness. Separate issue opened for this http://code.google.com/p/v8/issues/detail?id=877

BUG=http://code.google.com/p/v8/issues/detail?id=874

Committed: http://code.google.com/p/v8/source/detail?r=5512

[antonm, 2010-09-22 13:26:38]

Drive-bys

http://codereview.chromium.org/3462005/diff/1/4
File src/runtime.cc (right):

http://codereview.chromium.org/3462005/diff/1/4#newcode671
src/runtime.cc:671: elms->set(ENUMERABLE_INDEX,  Heap::true_value());
I am not sure all intercepted elements are enumerable.  You might prefer to use
query to find out precise attributes.

http://codereview.chromium.org/3462005/diff/1/5
File test/cctest/test-api.cc (right):

http://codereview.chromium.org/3462005/diff/1/5#newcode3028
test/cctest/test-api.cc:3028:
templ->SetIndexedPropertyHandler(IdentityIndexedPropertyGetter);
you probably need to extend this test case for cases when there are setters,
queries and enumerators are present.  But in real life (read, Chromium), we only
have getters, so realistically it's not bad a coverage.

[Rico, 2010-09-22 15:23:56]

Slava,
I am not a 100% clear on which cases we could hit with interceptors and what the
semantics should be. But other than that LGTM

http://codereview.chromium.org/3462005/diff/1/2
File src/objects.cc (right):

http://codereview.chromium.org/3462005/diff/1/2#newcode5962
src/objects.cc:5962: 
remove blank line?

http://codereview.chromium.org/3462005/diff/1/4
File src/runtime.cc (right):

http://codereview.chromium.org/3462005/diff/1/4#newcode685
src/runtime.cc:685: } else {
Add comment on why we would go in here