[ic] Support data handlers that represent simple field stores.

src/lookup.cc

Index: src/lookup.cc
diff --git a/src/lookup.cc b/src/lookup.cc
index 3921e1657c8511b5de5a1d96b6f802ae1649bbf0..1527032af76330bbe933391bc3078f09a2b64d3f 100644
--- a/src/lookup.cc
+++ b/src/lookup.cc
@@ -593,6 +593,12 @@ Handle<Object> LookupIterator::FetchValue() const {
   return handle(result, isolate_);
 }
 
+int LookupIterator::GetFieldDescriptorIndex() const {
+  DCHECK(has_property_);
+  DCHECK(holder_->HasFastProperties());
+  DCHECK_EQ(v8::internal::DATA, property_details_.type());
+  return descriptor_number();
+}
 
 int LookupIterator::GetAccessorIndex() const {
   DCHECK(has_property_);