The goal of WebAssembly is to open up the reach and easy user experience of the web browser to new types of applications that just aren't possible to build efficiently with current tech.
We're also making sure that wasm is a first-class citizen of the open web: see, for example, our thoughts around ES6 module interop, GC + DOM integration, and view-source to see the textual encoding of wasm [0][1].
[0]: https://github.com/WebAssembly/design/blob/master/Web.md
[1]: https://github.com/WebAssembly/design/blob/master/TextFormat...
(Disclaimer: I work on V8.)