adjust the stack after the if/if_else condition
adjust the stack after the if/if_else condition

Without this, anything that references the stack top in an if branch
will be off (e.g. local indexes).

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