Decoupling MarkDescriptorArray as much as possible from the ContentArray.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 544443866efc52a82fdb20f9b84db8540c1334fb..08c7078a134e3edaae7ea5e10642edac8b58bdc3 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -1929,6 +1929,12 @@ String* DescriptorArray::GetKey(int descriptor_number) {
 }
 
 
+Object** DescriptorArray::GetValueSlot(int descriptor_number) {
+  ASSERT(descriptor_number < number_of_descriptors());
+  return GetContentArray()->data_start() + ToValueIndex(descriptor_number);
+}
+
+
 Object* DescriptorArray::GetValue(int descriptor_number) {
   ASSERT(descriptor_number < number_of_descriptors());
   return GetContentArray()->get(ToValueIndex(descriptor_number));
@@ -1942,6 +1948,25 @@ PropertyDetails DescriptorArray::GetDetails(int descriptor_number) {
 }
 
 
+FixedArray* DescriptorArray::RawGetContentArray() {
+    Object* array = this->get(DescriptorArray::kContentArrayIndex);
+    return static_cast<FixedArray*>(array);
+}
+
+
+Object* DescriptorArray::RawGetValue(int descriptor_number) {
+  ASSERT(descriptor_number < number_of_descriptors());
+  return RawGetContentArray()->get(ToValueIndex(descriptor_number));
+}
+
+
+PropertyDetails DescriptorArray::RawGetDetails(int descriptor_number) {
+  ASSERT(descriptor_number < number_of_descriptors());
+  Object* details = RawGetContentArray()->get(ToDetailsIndex(descriptor_number));
+  return PropertyDetails(Smi::cast(details));
+}
+
+
 PropertyType DescriptorArray::GetType(int descriptor_number) {
   return GetDetails(descriptor_number).type();
 }