First cut at bug 992

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 724a4363483e0aa3a806f73cdb8a24fa8958441f..68cdb5121eeb6458a294736db12f4e7981b6abd8 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -3493,7 +3493,12 @@ static MaybeObject* Runtime_KeyedGetProperty(Arguments args) {
                                     args.at<Object>(1));
 }
 
-
+// Implements part of 8.12.9 DefineOwnProperty.
+// There are 3 cases that lead here:
+// Step 4b - define a new accessor property.
+// Steps 9c & 12 - replace an existing data property with an accessor property.
+// Step 12 - update an existing accessor property with an accessor or generic
+//           descriptor.
 static MaybeObject* Runtime_DefineOrRedefineAccessorProperty(Arguments args) {
   ASSERT(args.length() == 5);
   HandleScope scope;
@@ -3525,6 +3530,12 @@ static MaybeObject* Runtime_DefineOrRedefineAccessorProperty(Arguments args) {
   return obj->DefineAccessor(name, flag_setter->value() == 0, fun, attr);
 }
 
+// Implements part of 8.12.9 DefineOwnProperty.
+// There are 3 cases that lead here:
+// Step 4a - define a new data property.
+// Steps 9b & 12 - replace an existing accessor property with a data property.
+// Step 12 - update an existing data property with a data or generic
+//           descriptor.
 static MaybeObject* Runtime_DefineOrRedefineDataProperty(Arguments args) {
   ASSERT(args.length() == 4);
   HandleScope scope;