[cleanup] Delete unused method in DescriptorArray

Happily this also removes a use of GetIsolate().

Also delete Descriptor::Init which is no longer needed and some friend
declarations.

Bug: v8:7786
Change-Id: Ica803ef6c8963b38aef72121ff4fb737c9780920
Reviewed-on: https://chromium-review.googlesource.com/1133982Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54394}

src/objects-inl.h

@@ -2101,12 +2101,6 @@ FieldType* DescriptorArray::GetFieldType(int descriptor_number) {
   return Map::UnwrapFieldType(wrapped_type);
 }
 
-void DescriptorArray::Get(int descriptor_number, Descriptor* desc) {
-  desc->Init(handle(GetKey(descriptor_number), GetIsolate()),
-             MaybeObjectHandle(GetStrongValue(descriptor_number), GetIsolate()),
-             GetDetails(descriptor_number));
-}
-
 void DescriptorArray::Set(int descriptor_number, Name* key, MaybeObject* value,
                           PropertyDetails details) {
   // Range check.

src/objects/descriptor-array.h

@@ -85,7 +85,6 @@ class DescriptorArray : public WeakFixedArray {
   inline void SetSortedKey(int pointer, int descriptor_number);
 
   // Accessor for complete descriptor.
-  inline void Get(int descriptor_number, Descriptor* desc);
   inline void Set(int descriptor_number, Descriptor* desc);
   inline void Set(int descriptor_number, Name* key, MaybeObject* value,
                   PropertyDetails details);

src/property.h

@@ -65,15 +65,6 @@ class Descriptor final BASE_EMBEDDED {
   PropertyDetails details_;
 
  protected:
-  void Init(Handle<Name> key, MaybeObjectHandle value,
-            PropertyDetails details) {
-    DCHECK(key->IsUniqueName());
-    DCHECK_IMPLIES(key->IsPrivate(), !details.IsEnumerable());
-    key_ = key;
-    value_ = value;
-    details_ = details;
-  }
-
   Descriptor(Handle<Name> key, MaybeObjectHandle value, PropertyDetails details)
       : key_(key), value_(value), details_(details) {
     DCHECK(key->IsUniqueName());
@@ -92,8 +83,6 @@ class Descriptor final BASE_EMBEDDED {
     DCHECK_IMPLIES(key->IsPrivate(), !details_.IsEnumerable());
   }
 
-  friend class DescriptorArray;
-  friend class Map;
   friend class MapUpdater;
 };