Is it possible that emscripten (http://en.wikipedia.org/wiki/Emscripten) could be utilized with LDC? I've been interested in emscripten as it allows taking C++ code and compile it to JavaScript, with asm.js features. ASM.JS is a pain to write by hand, but it's great to use when a compiler targets it for you... resulting in 5-10x performance improvements in Firefox and around 3x in Chrome.

Rust is looking at using emscripten too:
https://github.com/Yoric/Mozilla-Student-Projects/issues/33