Fix issue 965.

src/v8natives.js

Index: src/v8natives.js
diff --git a/src/v8natives.js b/src/v8natives.js
index 50a2774d122072654cabadc5b8e0a9d8a4f81921..afa18cb4ddc20d0df8b0f9a29cfa075329edb8ec 100644
--- a/src/v8natives.js
+++ b/src/v8natives.js
@@ -615,7 +615,9 @@ function DefineOwnProperty(obj, p, desc, should_throw) {
     } else {
       flag |= READ_ONLY;
     }
-    %DefineOrRedefineDataProperty(obj, p, desc.getValue(), flag);
+    var value =

[Rico, 2010/12/10 10:42:35]

Maybe add a comment that states that this actually works even when no existing
value is present (since it defaults to undefined) - even when this is an
accessor.

[Kevin Millikin (Chromium), 2010/12/10 11:08:23]

I would actually suggest writing it just like the rest of the code in this
function: if (desc.hasValue()) { ... } else if (!IS_UNDEFINED(current)) { ... }
else { ... }.  There's no need for such a comment if you make the code clear and
explicit instead.  (It's especially surprising because it differs from all the
surrounding code, forcing the reader to think about it).

We will also generate slightly better code for IS_UNDEFINED(current) than using
conversion to boolean to test if it's undefined, so there's no reason to be
cryptic.

[Lasse Reichstein, 2010/12/10 11:21:45]

Changed to:
 var value;  // Default value is undefined.
    if (desc.hasValue()) {
      value = desc.getValue();
    } else if (!IS_UNDEFINED(current)) {
      value = current.getValue();
    }

[Kevin Millikin (Chromium), 2010/12/10 11:28:20]

I still think that's too cute.  This is a long function.  If someone writes "var
value = 0" somewhere above won't this break?

[Lasse Reichstein, 2010/12/10 11:37:51]

True, good point.
I'll make a new CL and make it 
 var value = void 0;

+        desc.hasValue() ? desc.getValue() : (current && current.getValue());
+    %DefineOrRedefineDataProperty(obj, p, value, flag);
   } else {
     if (desc.hasGetter() && IS_FUNCTION(desc.getGet())) {
        %DefineOrRedefineAccessorProperty(obj, p, GETTER, desc.getGet(), flag);