I could be wrong, but I think this is different. Are there any other languages that are both hosted on the JVM and also in Javascript VMs? Beyond that, there almost certainly isn't a lisp that is.
Parenscript doesn't have a runtime beyond what the JS implementation provides, so it's not really a Common Lisp running on JS, more like a way to compile Common Lisp-based DSLs to JavaScript. Red Daly's PSOS (https://github.com/gonzojive/paren-psos) library provides most of the runtime stuff, and I guess counts as a sort of implementation of CL. I've been toying with the idea of extending PSOS to a full CL in JavaScript.
x86 emulation is the wrong solution to this problem because of the difficulty of interop. Compiling to bytecode at least lets you treat JS functions as FFI calls. The first project to do this was Clue in 2008 (http://cluecc.sourceforge.net/), now all the hype is about emscripten (https://github.com/kripken/emscripten) LLVM bytecode to JS compiler.
Doing compilation GWT/Clojurescript style is going to reduce integration overhead. So far I haven't seen anything that integrates as well as Parenscript.
This is probably missing the point, but JavaScript is hosted on both the JVM and JavaScript VMs (thanks to Rhino). By extension, everything that compiles to JS is hosted on both.
Parenscript doesn't have a runtime beyond what the JS implementation provides, so it's not really a Common Lisp running on JS, more like a way to compile Common Lisp-based DSLs to JavaScript. Red Daly's PSOS (https://github.com/gonzojive/paren-psos) library provides most of the runtime stuff, and I guess counts as a sort of implementation of CL. I've been toying with the idea of extending PSOS to a full CL in JavaScript.