feat(text and css): html partials and css can be loaded via systemjs

public/vendor/plugin-css/css.js

@@ -0,0 +1,72 @@
+"use strict";
+
+if (typeof window !== 'undefined') {
+  var waitSeconds = 100;
+
+  var head = document.getElementsByTagName('head')[0];
+
+  // get all link tags in the page
+  var links = document.getElementsByTagName('link');
+  var linkHrefs = [];
+  for (var i = 0; i < links.length; i++) {
+    linkHrefs.push(links[i].href);
+  }
+
+  var isWebkit = !!window.navigator.userAgent.match(/AppleWebKit\/([^ ;]*)/);
+  var webkitLoadCheck = function(link, callback) {
+    setTimeout(function() {
+      for (var i = 0; i < document.styleSheets.length; i++) {
+        var sheet = document.styleSheets[i];
+        if (sheet.href === link.href) {
+          return callback();
+        }
+      }
+      webkitLoadCheck(link, callback);
+    }, 10);
+  };
+
+  var noop = function() {};
+
+  var loadCSS = function(url) {
+    return new Promise(function(resolve, reject) {
+      var timeout = setTimeout(function() {
+        reject('Unable to load CSS');
+      }, waitSeconds * 1000);
+      var _callback = function(error) {
+        clearTimeout(timeout);
+        link.onload = link.onerror = noop;
+        setTimeout(function() {
+          if (error) {
+            reject(error);
+          }
+          else {
+            resolve('');
+          }
+        }, 7);
+      };
+      var link = document.createElement('link');
+      link.type = 'text/css';
+      link.rel = 'stylesheet';
+      link.href = url;
+      if (!isWebkit) {
+        link.onload = function() {
+          _callback();
+        }
+      } else {
+        webkitLoadCheck(link, _callback);
+      }
+      link.onerror = function(event) {
+        _callback(event.error || new Error('Error loading CSS file.'));
+      };
+      head.appendChild(link);
+    });
+  };
+
+  exports.fetch = function(load) {
+    // dont reload styles loaded in the head
+    for (var i = 0; i < linkHrefs.length; i++)
+      if (load.address == linkHrefs[i])
+        return '';
+    return loadCSS(load.address);
+  };
+}