uglifyjs experiment (uglifyjs file.js --screw-ie8 -mc > file.min.js)

after.js

/**
// would need at least 3 arrays to prefix to bother pulling this out
var makePrefix = function(prefix){
  return function(e){
    return prefix + '-' + e;
  };
};
*/
[
// bower_components that we don't have enough of to map prefixes but that
//  do have matching folders
  'more-routing',
  'iron-pages', // not enough iron imports to establish a prefixer for
  'iron-icons'
].concat(
  [ // prefix these with paper-
    'drawer-panel',
    'toolbar',
    'icon-button',
    'menu',
    'input',
    'item'
  ].map(function(e){
    return 'paper-' + e;
  })
).map(function(e){
  return e + '/' + e + '.html';
}).concat([ // can't prefix or build paths to these
  'iron-flex-layout/classes/iron-flex-layout.html'
]).map(function(e){
  return '../bower_components/' + e;
}).concat([ // imports that aren't in bower components
  'imports/more-routing-config.html'
]).forEach(function(elementURL){
  var elImport = document.createElement('link');
  elImport.rel = 'import';
  elImport.href = elementURL;

  document.head.appendChild(elImport);
});

after.min.js

["more-routing","iron-pages","iron-icons"].concat(["drawer-panel","toolbar","icon-button","menu","input","item"].map(function(n){return"paper-"+n})).map(function(n){return n+"/"+n+".html"}).concat(["iron-flex-layout/classes/iron-flex-layout.html"]).map(function(n){return"../bower_components/"+n}).concat(["imports/more-routing-config.html"]).forEach(function(n){var o=document.createElement("link");o.rel="import",o.href=n,document.head.appendChild(o)});

before.js

[
  "../bower_components/iron-flex-layout/classes/iron-flex-layout.html",
  "../bower_components/paper-drawer-panel/paper-drawer-panel.html",
  "../bower_components/paper-toolbar/paper-toolbar.html",
  "../bower_components/paper-icon-button/paper-icon-button.html",
  "../bower_components/paper-menu/paper-menu.html",
  "../bower_components/paper-item/paper-item.html",
  "../bower_components/paper-input/paper-input.html",
  "../bower_components/iron-pages/iron-pages.html",
  "../bower_components/iron-icons/iron-icons.html",
  "../bower_components/more-routing/more-routing.html",
  "imports/more-routing-config.html"
].forEach(function(elementURL){
  var elImport = document.createElement("link");
  elImport.rel = "import";
  elImport.href = elementURL;

  document.head.appendChild(elImport);
})

before.min.js

["../bower_components/iron-flex-layout/classes/iron-flex-layout.html","../bower_components/paper-drawer-panel/paper-drawer-panel.html","../bower_components/paper-toolbar/paper-toolbar.html","../bower_components/paper-icon-button/paper-icon-button.html","../bower_components/paper-menu/paper-menu.html","../bower_components/paper-item/paper-item.html","../bower_components/paper-input/paper-input.html","../bower_components/iron-pages/iron-pages.html","../bower_components/iron-icons/iron-icons.html","../bower_components/more-routing/more-routing.html","imports/more-routing-config.html"].forEach(function(o){var e=document.createElement("link");e.rel="import",e.href=o,document.head.appendChild(e)});

see https://aerotwist.com/blog/polymer-for-the-performance-obsessed/ for the source of the foreach func