Yes, but JavaScript can't be compiled to efficient WASM code. Dynamic-dispatch languages need an optimizing JIT -- compiling once runtime behavior is known -- to produce good machine code. In any event, it seems like it's a planned feature for a some future release.
(We may not be in disagreement here—I agree that JS can't be effectively compiled to Web Assembly as it stands.)
The design documents clearly state that WASM is intended to be a compilation target for C-like languages, and in the future may also contain a GC and an optimizing JIT.
Languages requiring a GC and/or not amenable to AOT optimization should -- at least for the time being -- continue to target JS as a compilation target (or implement their own runtime in a C-like language and embed it in WASM).
WebAssembly should support:
Producing a dynamic library and loading it into the current WebAssembly module.
Define lighter-weight mechanisms, such as the ability to add a function to an existing module.
Support explicitly patchable constructs within functions to allow for very fine-grained JIT-compilation. This includes:
Code patching for polymorphic inline caching;
Call patching to chain JIT-compiled functions together;
Temporary halt-insertion within functions, to trap if a function start executing while a JIT-compiler's runtime is performing operations dangerous to that function.
Provide JITs access to profile feedback for their JIT-compiled code.
Code unloading capabilities, especially in the context of code garbage collection and defragmentation.