Fix issue 1447 by not redefining properties unneccesarily in seal and freeze.

Fix issue 1447 by not redefining properties unneccesarily in seal and freeze.

This avoids attempting to redefine function.arguments with a different
value than the current one. function.arguments returns a new copy on
each invocation.

R=lrn@chromium.org
BUG=v8:1447
TEST=mjsunit/regress/regress-1447.js

Committed: http://code.google.com/p/v8/source/detail?r=8258

[Lasse Reichstein, 2011-06-10 09:09:10]

LGTM

http://codereview.chromium.org/7044104/diff/1/src/v8natives.js
File src/v8natives.js (right):

http://codereview.chromium.org/7044104/diff/1/src/v8natives.js#newcode942
src/v8natives.js:942: desc.setConfigurable(false);
Make it 
 if (desc.isConfigurable()) {
   ...
 }
instead of using continue. More readable, since it makes control flow visible by
indentation.

http://codereview.chromium.org/7044104/diff/1/src/v8natives.js#newcode958
src/v8natives.js:958: if (!desc.isWritable() && !desc.isConfigurable())
continue;
Ditto here: invert the condition and put the rest of the loop inside the if. And
drop the tests before setting Writable and Configurable to false.

[Mads Ager (chromium), 2011-06-10 09:13:41]

http://codereview.chromium.org/7044104/diff/1/src/v8natives.js
File src/v8natives.js (right):

http://codereview.chromium.org/7044104/diff/1/src/v8natives.js#newcode942
src/v8natives.js:942: desc.setConfigurable(false);
On 2011/06/10 09:09:10, Lasse Reichstein wrote:
> Make it 
>  if (desc.isConfigurable()) {
>    ...
>  }
> instead of using continue. More readable, since it makes control flow visible
by
> indentation.

Done.

http://codereview.chromium.org/7044104/diff/1/src/v8natives.js#newcode958
src/v8natives.js:958: if (!desc.isWritable() && !desc.isConfigurable())
continue;
On 2011/06/10 09:09:10, Lasse Reichstein wrote:
> Ditto here: invert the condition and put the rest of the loop inside the if.
And
> drop the tests before setting Writable and Configurable to false.

Done.