I wrote a book chapter in the upcoming book "WebGL Insights" to be published in August on just the subject. The answer is yes, if you port your OpenGL ES 1.0 code to OpenGL ES 2.0. The WebGL 1.0 spec is basically just a diff of the ES 2.0 spec. Then Emscripten can do most of the rest. I'm assuming your code is C++.
