Splitting interop support so `dart_support.js` is no longer required.

pkg/web_components/lib/dart_support.js

Index: pkg/web_components/lib/dart_support.js
diff --git a/pkg/web_components/lib/dart_support.js b/pkg/web_components/lib/dart_support.js
index 7ce882cef9a107d18d5fc8ec23de4d7df69673d8..3f712ef6019755bda7052d0f16c62423cebec98f 100644
--- a/pkg/web_components/lib/dart_support.js
+++ b/pkg/web_components/lib/dart_support.js
@@ -66,123 +66,3 @@
     }
   });
 })();
-
-// Updates document.registerElement so Dart can see when Javascript custom
-// elements are created, and wrap them to provide a Dart friendly API.
-(function (doc) {
-  var upgraders = {};       // upgrader associated with a custom-tag.
-  var unpatchableTags = {}; // set of custom-tags that can't be patched.
-  var pendingElements = {}; // will upgrade when/if an upgrader is installed.
-  var upgradeOldElements = true;
-
-  var originalRegisterElement = doc.registerElement;
-  if (!originalRegisterElement) {
-    throw new Error('document.registerElement is not present.');
-  }
-
-  function reportError(name) {
-    console.error("Couldn't patch prototype to notify Dart when " + name +
-        " elements are created. This can be fixed by making the " +
-        "createdCallback in " + name + " a configurable property.");
-  }
-
-  function registerElement(name, options) {
-    var proto, extendsOption;
-    if (options !== undefined) {
-      proto = options.prototype;
-    } else {
-      proto = Object.create(HTMLElement.prototype);
-      options = {protoptype: proto};
-    }
-
-    var original = proto.createdCallback;
-    var newCallback = function() {
-      original.call(this);
-      var name = (this.getAttribute('is') || this.localName).toLowerCase();
-      var upgrader = upgraders[name];
-      if (upgrader) {
-        upgrader(this);
-      } else if (upgradeOldElements) {
-        // Save this element in case we can upgrade it later when an upgrader is
-        // registered.
-        var list = pendingElements[name];
-        if (!list) {
-          list = pendingElements[name] = [];
-        }
-        list.push(this);
-      }
-    };
-
-    var descriptor = Object.getOwnPropertyDescriptor(proto, 'createdCallback');
-    if (!descriptor || descriptor.writable) {
-      proto.createdCallback = newCallback;
-    } else if (descriptor.configurable) {
-      descriptor['value'] = newCallback;
-      Object.defineProperty(proto, 'createdCallback', descriptor);
-    } else {
-      unpatchableTags[name] = true;
-      if (upgraders[name]) reportError(name);
-    }
-    return originalRegisterElement.call(this, name, options);
-  }
-
-  function registerDartTypeUpgrader(name, upgrader) {
-    if (!upgrader) return;
-    name = name.toLowerCase();
-    var existing = upgraders[name];
-    if (existing) {
-      console.error('Already have a Dart type associated with ' + name);
-      return;
-    }
-    upgraders[name] = upgrader;
-    if (unpatchableTags[name]) reportError(name);
-    if (upgradeOldElements) {
-      // Upgrade elements that were created before the upgrader was registered.
-      var list = pendingElements[name];
-      if (list) {
-        for (var i = 0; i < list.length; i++) {
-          upgrader(list[i]);
-        }
-      }
-      delete pendingElements[name];
-    } else {
-      console.warn("Didn't expect more Dart types to be registered. '" + name
-          + "' elements that already exist in the page might not be wrapped.");
-    }
-  }
-
-  function onlyUpgradeNewElements() {
-    upgradeOldElements = false;
-    pendingElements = null;
-  }
-
-  // Native custom elements outside the app in Chrome have constructor
-  // names like "x-tag", which need to be translated to the DOM
-  // element they extend.  When using the shadow dom polyfill this is
-  // take care of above.
-  var ShadowDOMPolyfill = window.ShadowDOMPolyfill;
-  if (!ShadowDOMPolyfill) {
-    // dartNativeDispatchHooksTransformer is described on initHooks() in
-    // sdk/lib/_internal/lib/native_helper.dart.
-    if (typeof window.dartNativeDispatchHooksTransformer == 'undefined')
-    window.dartNativeDispatchHooksTransformer = [];
-
-    window.dartNativeDispatchHooksTransformer.push(function(hooks) {
-      var originalGetUnknownTag = hooks.getUnknownTag;
-      hooks.getUnknownTag = function(o, tag) {
-        if (/-/.test(tag)) {  // "x-tag"
-          var s = Object.prototype.toString.call(o);
-          var match = s.match(/^\[object ([A-Za-z]*Element)\]$/);
-          if (match) {
-            return match[1];
-	  }
-          return originalGetUnknownTag(o, tag);
-        }
-      };
-    });
-  }
-
-  doc._registerDartTypeUpgrader = registerDartTypeUpgrader;
-  doc._onlyUpgradeNewElements = onlyUpgradeNewElements;
-  doc.registerElement = registerElement;
-})(document);