New version of dart:html

client/html/src/Measurement.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 typedef Object ComputeValue();
 
 class _MeasurementRequest<T> {
   final ComputeValue computeValue;
   final Completer<T> completer;
   Object value;
@@ skipping 68 matching lines @@
 void _completeMeasurementFutures() {
   if (_nextMeasurementFrameScheduled == false) {
     // Ignore spurious call to this function.
     return;
   }
 
   _nextMeasurementFrameScheduled = false;
   // We must compute all new values before fulfilling the futures as
   // the onComplete callbacks for the futures could modify the DOM making
   // subsequent measurement calculations expensive to compute.
-  for (_MeasurementRequest request in _pendingRequests) {
-    try {
-      request.value = request.computeValue();
-    } catch(var e) {
-      request.value = e;
-      request.exception = true;
+  if (_pendingRequests !== null) {
+    for (_MeasurementRequest request in _pendingRequests) {
+      try {
+        request.value = request.computeValue();
+      } catch(var e) {
+        request.value = e;
+        request.exception = true;
+      }
     }
   }
 
   final completedRequests = _pendingRequests;
   final readyMeasurementFrameCallbacks = _pendingMeasurementFrameCallbacks;
   _pendingRequests = null;
   _pendingMeasurementFrameCallbacks = null;
-  for (_MeasurementRequest request in completedRequests) {
-    if (request.exception) {
-      request.completer.completeException(request.value);
-    } else {
-      request.completer.complete(request.value);
+  if (completedRequests !== null) {
+    for (_MeasurementRequest request in completedRequests) {
+      if (request.exception) {
+        request.completer.completeException(request.value);
+      } else {
+        request.completer.complete(request.value);
+      }
     }
   }
 
   if (readyMeasurementFrameCallbacks !== null) {
     for (TimeoutHandler handler in readyMeasurementFrameCallbacks) {
       // TODO(jacobr): wrap each call to a handler in a try-catch block.
       handler();
     }
   }
 }