cherry pick to fix memory leak

pkg/web_components/lib/platform.concat.js

Index: pkg/web_components/lib/platform.concat.js
diff --git a/pkg/web_components/lib/platform.concat.js b/pkg/web_components/lib/platform.concat.js
index 9b7ff43b306605248f61313126fcba359fd2e5f2..bf10fe7149cbe2065ae214e23382f3bfcf99e759 100644
--- a/pkg/web_components/lib/platform.concat.js
+++ b/pkg/web_components/lib/platform.concat.js
@@ -1,71 +1,3 @@
-/**
- * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.

[Siggi Cherem (dart-lang), 2014/09/10 22:13:52]

seems odd that this part is removed?

[jakemac, 2014/09/10 22:37:43]

fixed

- * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
- * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
- * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
- * Code distributed by Google as part of the polymer project is also
- * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
- */
-
-window.Platform = window.Platform || {};
-// prepopulate window.logFlags if necessary
-window.logFlags = window.logFlags || {};
-// process flags
-(function(scope){
-  // import
-  var flags = scope.flags || {};
-  // populate flags from location
-  location.search.slice(1).split('&').forEach(function(o) {
-    o = o.split('=');
-    o[0] && (flags[o[0]] = o[1] || true);
-  });
-  var entryPoint = document.currentScript ||
-      document.querySelector('script[src*="platform.js"]');
-  if (entryPoint) {
-    var a = entryPoint.attributes;
-    for (var i = 0, n; i < a.length; i++) {
-      n = a[i];
-      if (n.name !== 'src') {
-        flags[n.name] = n.value || true;
-      }
-    }
-  }
-  if (flags.log) {
-    flags.log.split(',').forEach(function(f) {
-      window.logFlags[f] = true;
-    });
-  }
-  // If any of these flags match 'native', then force native ShadowDOM; any
-  // other truthy value, or failure to detect native
-  // ShadowDOM, results in polyfill
-  flags.shadow = flags.shadow || flags.shadowdom || flags.polyfill;
-  if (flags.shadow === 'native') {
-    flags.shadow = false;
-  } else {
-    flags.shadow = flags.shadow || !HTMLElement.prototype.createShadowRoot;
-  }
-
-  if (flags.shadow && document.querySelectorAll('script').length > 1) {
-    console.warn('platform.js is not the first script on the page. ' +
-        'See http://www.polymer-project.org/docs/start/platform.html#setup ' +
-        'for details.');
-  }
-
-  // CustomElements polyfill flag
-  if (flags.register) {
-    window.CustomElements = window.CustomElements || {flags: {}};
-    window.CustomElements.flags.register = flags.register;
-  }
-
-  if (flags.imports) {
-    window.HTMLImports = window.HTMLImports || {flags: {}};
-    window.HTMLImports.flags.imports = flags.imports;
-  }
-
-  // export
-  scope.flags = flags;
-})(Platform);
-
 /*
  * Copyright 2012 The Polymer Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style
@@ -112,9 +44,6 @@ if (typeof WeakMap === 'undefined') {
   })();
 }
 
-// select ShadowDOM impl
-if (Platform.flags.shadow) {
-
 // Copyright 2012 Google Inc.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
@@ -2327,7 +2256,7 @@ window.ShadowDOMPolyfill = {};
   var globalMutationObservers = [];
   var isScheduled = false;
 
-  function scheduleCallback(observer) {
+  function scheduleCallback() {
     if (isScheduled)
       return;
     setEndOfMicrotask(notifyObservers);
@@ -2338,21 +2267,25 @@ window.ShadowDOMPolyfill = {};
   function notifyObservers() {
     isScheduled = false;
 
-    do {
-      var notifyList = globalMutationObservers.slice();
-      var anyNonEmpty = false;
+    while (globalMutationObservers.length) {
+      var notifyList = globalMutationObservers;
+      globalMutationObservers = [];
+
+      // Deliver changes in birth order of the MutationObservers.
+      notifyList.sort(function(x, y) { return x.uid_ - y.uid_; });
+
       for (var i = 0; i < notifyList.length; i++) {
         var mo = notifyList[i];
         var queue = mo.takeRecords();
         removeTransientObserversFor(mo);
         if (queue.length) {
           mo.callback_(queue, mo);
-          anyNonEmpty = true;
         }
       }
-    } while (anyNonEmpty);
+    }
   }
 
+
   /**
    * @param {string} type
    * @param {Node} target
@@ -2458,7 +2391,7 @@ window.ShadowDOMPolyfill = {};
       }
     }
 
-    var anyRecordsEnqueued = false;
+    var anyObserversEnqueued = false;
 
     // 4.
     for (var uid in interestedObservers) {
@@ -2492,12 +2425,14 @@ window.ShadowDOMPolyfill = {};
         record.oldValue = associatedStrings[uid];
 
       // 8.
+      if (!observer.records_.length) {
+        globalMutationObservers.push(observer);
+        anyObserversEnqueued = true;
+      }
       observer.records_.push(record);
-
-      anyRecordsEnqueued = true;
     }
 
-    if (anyRecordsEnqueued)
+    if (anyObserversEnqueued)
       scheduleCallback();
   }
 
@@ -2561,9 +2496,6 @@ window.ShadowDOMPolyfill = {};
     this.nodes_ = [];
     this.records_ = [];
     this.uid_ = ++uidCounter;
-
-    // This will leak. There is no way to implement this without WeakRefs :'(
-    globalMutationObservers.push(this);
   }
 
   MutationObserver.prototype = {
@@ -8883,7 +8815,6 @@ scope.ShadowCSS = ShadowCSS;
 
 })(window.Platform);
 
-} else {
 /*
  * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
  * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
@@ -8913,7 +8844,6 @@ scope.ShadowCSS = ShadowCSS;
 
 })(window.Platform);
 
-}
 /* Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/ */