message: change for cargo_metadata
diff: //! Functionality related to installing and running `wasm-bindgen`.
  use binaries::{self, bin_path, install_binaries_from_targz_at_url};
  +use cargo_metadata;
  use emoji;
  use error::Error;
  use progressbar::Step;
  use slog::Logger;
  -use std::env;
  use std::path::{Path, PathBuf};
  use std::process::Command;
  use target;
  @@ -127,11 +127,11 @@ pub fn wasm_bindgen_build(
  let out_dir = out_dir.to_str().unwrap();
  if let Some(wasm_bindgen_path) = wasm_bindgen_path(log, path) {
  - let target_path = match env::var("CARGO_TARGET_DIR") {
  - Ok(path) => PathBuf::from(&path),
  - Err(_) => PathBuf::from("target"),
  - };
  - let mut wasm_path = target_path
  + let manifest = path.join("Cargo.toml");
  + let target_path = cargo_metadata::metadata(Some(&manifest))
  + .unwrap()
  + .target_directory;
  + let mut wasm_path = PathBuf::from(&target_path)
  .join("wasm32-unknown-unknown")
  .join(release_or_debug)
  .join(binary_name);
  