src: inspect properties with descriptor details

When the PropertyLocation of the details of a JSObject property is
kDescriptor, we can just get the descriptor from the descriptors array
and inspect it. This solves several fields being resolved as
`<unknown field type>`.

Fixes: #198
Ref: #209

PR-URL: #221
Refs: #209
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

Author: Matheus Marchini

src/llv8-inl.h

@@ -476,6 +476,18 @@ inline Value DescriptorArray::GetValue(int index, Error& err) {
                     err);
 }
 
+inline bool DescriptorArray::IsDescriptorDetails(Smi details) {
+  // node.js <= 7
+  if (v8()->descriptor_array()->kPropertyTypeMask != -1) {
+    return false;
+  }
+
+  // node.js >= 8
+  return (details.GetValue() &
+          v8()->descriptor_array()->kPropertyLocationMask) ==
+         (v8()->descriptor_array()->kPropertyLocationEnum_kDescriptor
+          << v8()->descriptor_array()->kPropertyLocationShift);
+}
 inline bool DescriptorArray::IsFieldDetails(Smi details) {
   // node.js <= 7
   if (v8()->descriptor_array()->kPropertyTypeMask != -1) {

src/llv8.cc

@@ -1516,7 +1516,7 @@ std::string JSObject::InspectDescriptors(Map map, Error& err) {
     res += "    ." + key.ToString(err) + "=";
     if (err.Fail()) return std::string();
 
-    if (descriptors.IsConstFieldDetails(details)) {
+    if (descriptors.IsConstFieldDetails(details) || descriptors.IsDescriptorDetails(details)) {
       Value value;
 
       value = descriptors.GetValue(i, err);
@@ -1527,14 +1527,6 @@ std::string JSObject::InspectDescriptors(Map map, Error& err) {
       continue;
     }
 
-    // Skip non-fields for now
-    if (!descriptors.IsFieldDetails(details)) {
-      Error::PrintInDebugMode("Unknown field Type %" PRId64,
-                              details.GetValue());
-      res += "<unknown field type>";
-      continue;
-    }
-
     int64_t index = descriptors.FieldIndex(details) - in_object_count;
 
     if (descriptors.IsDoubleField(details)) {

src/llv8.h

@@ -363,6 +363,7 @@ class DescriptorArray : public FixedArray {
   inline Value GetValue(int index, Error& err);
 
   inline bool IsFieldDetails(Smi details);
+  inline bool IsDescriptorDetails(Smi details);
   inline bool IsConstFieldDetails(Smi details);
   inline bool IsDoubleField(Smi details);
   inline int64_t FieldIndex(Smi details);