message: Only shim when we build vega-embed
diff: "scripts": {
  "deploy": "npm run lint && scripts/deploy.sh",
  "lint": "eslint src/",
  - "build": "browserify src/embed.js -d -s vega.embed > vega-embed.js",
  + "build": "browserify src/embed.js -t browserify-shim -d -s vega.embed > vega-embed.js",
  "postbuild": "uglifyjs vega-embed.js -cm > vega-embed.min.js",
  - "watch": "watchify src/embed.js -v -d -s vega.embed -o vega-embed.js"
  - },
  - "browserify": {
  - "transform": [
  - "browserify-shim"
  - ]
  + "watch": "watchify src/embed.js -t browserify-shim -v -d -s vega.embed -o vega-embed.js"
  },
  "browserify-shim": {
  "vega": "global:vega",
  