Getting the File Size of an Object on Amazon S3 - PHP SDK

I am currently using the PHP SDK for AWS. I read Dynamically Get Size of Files in Amazon S3 Bucket, but noticed that the methods mentioned to get an object's file size are no longer available in the latest SDK. I've also read through the PHP SDK documentation and wasn't able to find anything on how to find the file size of an object.

How would I get the file size of an object using the latest PHP SDK (version 2.7)?