fix bug when writing nan tags
fix bug when writing nan tags

We shouldn't trim trailing zeroes when writing the nan tag.

WebAssembly/sexpr-wasm-prototype,WebAssembly/wabt,citisolo/wabt,WebAssembly/sexpr-wasm-prototype,citisolo/wabt,WebAssembly/sexpr-wasm-prototype,WebAssembly/sexpr-wasm-prototype,citisolo/wabt,WebAssembly/wabt,WebAssembly/wabt,citisolo/wabt,WebAssembly/sexpr-wasm-prototype,WebAssembly/sexpr-wasm-prototype,WebAssembly/wabt,citisolo/wabt,WebAssembly/wabt,citisolo/wabt