Bug 1002737 - Assert more about PropDesc definedness in various functions. (r=jorendorff)

js/src/jsobj.cpp

@@ -275,6 +275,8 @@ js::NewPropertyDescriptorObject(JSContext *cx, Handle<PropertyDescriptor> desc,
 void
 PropDesc::initFromPropertyDescriptor(Handle<PropertyDescriptor> desc)
 {
+    MOZ_ASSERT(isUndefined());
+
     isUndefined_ = false;
     descObj_ = nullptr;
     attrs = uint8_t(desc.attributes());
@@ -433,6 +435,8 @@ HasProperty(JSContext *cx, HandleObject obj, HandleId id, MutableHandleValue vp,
 bool
 PropDesc::initialize(JSContext *cx, const Value &origval, bool checkAccessors)
 {
+    MOZ_ASSERT(isUndefined());
+
     RootedValue v(cx, origval);
 
     /* 8.10.5 step 1 */
@@ -535,6 +539,8 @@ PropDesc::initialize(JSContext *cx, const Value &origval, bool checkAccessors)
 void
 PropDesc::complete()
 {
+    MOZ_ASSERT(!isUndefined());
+
     if (isGenericDescriptor() || isDataDescriptor()) {
         if (!hasValue_) {
             hasValue_ = true;