jssource/src_files directory missing?

Yes, it is expected that it disappear. The unminified sources are now in ./clients. This was done to eliminate some redundancies in the code. 

Any references that you might still find to ./jssource/src_files would be in error.

Good to know! I'll need to make a note of that as I am sure to forget

FYI - a quick grep gives me:

jssource/minify_utils.php:        $bu_path .= substr($from_path, strlen($to_path.'/jssource/src_files'));

jssource/minify_utils.php:            $bu_path = $to_path.'/jssource/src_files';

jssource/minify.php:            $minifyUtils->reverseScripts("$from/jssource/src_files",$from);

jssource/minify.php:            $minifyUtils->reverseScripts("$from/jssource/src_files",$from);

jssource/minify.php:            $minifyUtils->reverseScripts("$from/jssource/src_files",$from);

jssource/minify.php:     -r  = replace javascript of root with scripts from backed up jssource/src_files directory

modules/Administration/callJSRepair.php:            $minifyUtils->reverseScripts("$from/jssource/src_files","$from");

modules/Administration/callJSRepair.php:            $minifyUtils->reverseScripts("$from/jssource/src_files","$from");

Thanks Francesca.  I'll share with Engineering team and see what they say. There may be a reason for preserving these directories (perhaps out of an abundance of caution in preserving unsafe customizations).

Also - we blogged about this change in JavaScript handling earlier this year.

Handling of JavaScript files in Sugar 7.7 « Sugar Developer Blog – SugarCRM 

I do believe most if not all those occurrences are conditional.

Thank you for the Blog reference Matt Marum I probably read it and dismissed it since I'm only just now getting to the 7.7 upgrade.