A mix of Smalltalk luminaries have resurrected Smalltalk-78 (a port of Smalltalk-76 to an early 8086 prototype luggable called NoteTaker http://bitsavers.trailing-edge.com/pdf/xerox/notetaker/) and it runs in a modern web-browser using Javascript (even runs on an iPad but will need changes to support touch).
http://lively-web.org/users/bert/Smalltalk-78.html PDF describing what they did here: http://www.freudenbergs.de/bert/publications/Ingalls-2014-Smalltalk78.pdf According to this document there is yet to be published Java implementation too. A 35-minute video presentation: https://www.youtube.com/watch?v=pTh65b8qSY8 https://www.youtube.com/watch?v=R3t13RHO3X8 Smalltalk-78 compliments the Smalltalk-72 Alto emulator from Dan Ingalls released in 2013, although the link I found doesn't seem to work anymore: http://lively-web.org/users/Dan/ALTO-Smalltalk-72.html. It almost works, but the display is messed up on Safari/Chrome.