introduce web_components pkg for consolidated polyfills

pkg/html_import/lib/tools/loader/loader.js

-/*
- * Copyright 2013 The Polymer Authors. All rights reserved.
- * Use of this source code is governed by a BSD-style
- * license that can be found in the LICENSE file.
- */
-
-(function() {
-  
-var scope = window.Loader = {};
-var flags = {};
-
-// convert url arguments to flags
-
-if (!flags.noOpts) {
-  location.search.slice(1).split('&').forEach(function(o) {
-    o = o.split('=');
-    o[0] && (flags[o[0]] = o[1] || true);
-  });
-}
-
-// process global logFlags
-
-parseLogFlags(flags);
-
-function load(scopeName) {
-  // imports
-
-  var scope = window[scopeName];
-  var entryPointName = scope.entryPointName;
-  var processFlags = scope.processFlags;
-
-  // acquire attributes and base path from entry point
-
-  var entryPoint = findScript(entryPointName);
-  var base = entryPoint.basePath;
-  
-  // acquire common flags
-  var flags = Loader.flags;
-
-  // convert attributes to flags
-  var flags = Loader.flags;
-  for (var i=0, a; (a=entryPoint.attributes[i]); i++) {
-    if (a.name !== 'src') {
-      flags[a.name] = a.value || true;
-    }
-  }
-
-  // parse log flags into global
-  parseLogFlags(flags);
-
-  // exports
-
-  scope.basePath = base;
-  scope.flags = flags;
-
-  // process flags for dynamic dependencies
-
-  if (processFlags) {
-    processFlags.call(scope, flags);
-  }
-
-  // post-process imports
-
-  var modules = scope.modules || [];
-  var sheets = scope.sheets || [];
-
-  // write script tags for dependencies
-
-  modules.forEach(function(src) {
-    document.write('<script src="' + base + src + '"></script>');
-  });
-
-  // write link tags for styles
-
-  sheets.forEach(function(src) {
-    document.write('<link rel="stylesheet" href="' + base + src + '">');
-  }); 
-}
-
-// utility method
-
-function findScript(fileName) {
-  var script = document.querySelector('script[src*="' + fileName + '"]');
-  var src = script.attributes.src.value;
-  script.basePath = src.slice(0, src.indexOf(fileName));
-  return script;
-}
-
-function parseLogFlags(flags) {
-  var logFlags = window.logFlags = window.logFlags || {};
-  if (flags.log) {
-    flags.log.split(',').forEach(function(f) {
-      logFlags[f] = true;
-    });
-  }
-}
-
-scope.flags = flags;
-scope.load = load;  
-
-})();