Object.observe: Make array length and other magic data properties work correctly.

src/property.h

Index: src/property.h
diff --git a/src/property.h b/src/property.h
index c41c6dc816727db4dee43fab4638656891adcbe1..168b80a11a86c9cd397eadaf29321ad4d083fb5c 100644
--- a/src/property.h
+++ b/src/property.h
@@ -310,6 +310,19 @@ class LookupResult BASE_EMBEDDED {
     return IsFound() && !IsTransition();
   }
 
+  bool IsDataProperty() {
+    switch (type()) {
+      case FIELD:
+      case NORMAL:
+      case CONSTANT_FUNCTION:
+        return true;
+      case CALLBACKS:
+        return GetCallbackObject()->IsForeign();

[Michael Starzinger, 2012/12/12 15:34:05]

I think AccessorInfo callbacks should also return true here, they also look like
data properties to JavaScript.

[rossberg, 2012/12/12 15:41:10]

Done.

+      default:

[Michael Starzinger, 2012/12/12 15:34:05]

I think Sven has to say something about this default case.

[rossberg, 2012/12/12 15:41:10]

Unfolded default (also in GetLazyValue below).

+        return false;
+    }
+  }
+
   bool IsCacheable() { return cacheable_; }
   void DisallowCaching() { cacheable_ = false; }