LibWeb: Remove unused underlying_buffer_source function

This function is not used anywhere and will most likely end up causing
problems so just remove it.

Author: devgianlu

Libraries/LibWeb/WebIDL/AbstractOperations.cpp

@@ -33,18 +33,6 @@ bool is_buffer_source_type(JS::Value value)
     return is<JS::TypedArrayBase>(object) || is<JS::DataView>(object) || is<JS::ArrayBuffer>(object);
 }
 
-GC::Ptr<JS::ArrayBuffer> underlying_buffer_source(JS::Object& buffer_source)
-{
-    if (is<JS::TypedArrayBase>(buffer_source))
-        return static_cast<JS::TypedArrayBase&>(buffer_source).viewed_array_buffer();
-    if (is<JS::DataView>(buffer_source))
-        return static_cast<JS::DataView&>(buffer_source).viewed_array_buffer();
-    if (is<JS::ArrayBuffer>(buffer_source))
-        return static_cast<JS::ArrayBuffer&>(buffer_source);
-
-    VERIFY_NOT_REACHED();
-}
-
 // https://webidl.spec.whatwg.org/#dfn-get-buffer-source-copy
 ErrorOr<ByteBuffer> get_buffer_source_copy(JS::Object const& buffer_source)
 {