Makes typical property creation faster.

Some code and benchmarks such as
http://www2.webkit.org/perf/sunspider-0.9/access-binary-trees.html
create properties almost as often as they use them. These frequent
property creations are of absent properties on extensible objects, so
I added a shortcut to .w___ for that case. access-binary-trees.html is
now about twice as fast.

[metaweta, 2010-09-21 22:43:16]

LGTM.

http://codereview.appspot.com/2192044/diff/1/src/com/google/caja/es53.js
File src/com/google/caja/es53.js (right):

http://codereview.appspot.com/2192044/diff/1/src/com/google/caja/es53.js#newc...
src/com/google/caja/es53.js:4504: name = '' + name;
Ankur pointed out that these aren't interchangeable; this form invokes valueOf
first.  I need to go back and check all the places where either form is used and
make sure we're doing the right thing.

[metaweta, 2011-08-22 16:41:58]

On 2010/09/21 22:43:16, metaweta wrote:
> LGTM.
> 
> http://codereview.appspot.com/2192044/diff/1/src/com/google/caja/es53.js
> File src/com/google/caja/es53.js (right):
> 
>
http://codereview.appspot.com/2192044/diff/1/src/com/google/caja/es53.js#newc...
> src/com/google/caja/es53.js:4504: name = '' + name;
> Ankur pointed out that these aren't interchangeable; this form invokes valueOf
> first.  I need to go back and check all the places where either form is used
and
> make sure we're doing the right thing.

What's the status of this CL?