IDL: Use Nullable for union type return value

Source/core/animation/AnimationNodeTiming.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/animation/AnimationNodeTiming.h"
 
 #include "core/animation/Animation.h"
 #include "core/animation/AnimationNode.h"
 #include "platform/animation/TimingFunction.h"
@@ skipping 47 matching lines @@
 
 double AnimationNodeTiming::iterations()
 {
     return m_parent->specifiedTiming().iterationCount;
 }
 
 // This logic was copied from the example in bindings/tests/idls/TestInterface.idl
 // and bindings/tests/results/V8TestInterface.cpp.
 // FIXME: It might be possible to have 'duration' defined as an attribute in the idl.
 // If possible, fix will be in a follow-up patch.
-void AnimationNodeTiming::getDuration(String propertyName, bool& element0Enabled, double& element0, bool& element1Enabled, String& element1)
+void AnimationNodeTiming::getDuration(String propertyName, Nullable<double>& element0, String& element1)
 {
     if (propertyName != "duration")
         return;
 
     if (std::isnan(m_parent->specifiedTiming().iterationDuration)) {
-        element1Enabled = true;
         element1 = "auto";
         return;
     }
-    element0Enabled = true;
-    element0 = m_parent->specifiedTiming().iterationDuration * 1000;
+    element0.set(m_parent->specifiedTiming().iterationDuration * 1000);
     return;
 }
 
 double AnimationNodeTiming::playbackRate()
 {
     return m_parent->specifiedTiming().playbackRate;
 }
 
 String AnimationNodeTiming::direction()
 {
@@ skipping 82 matching lines @@
     TimingInput::setTimingFunction(timing, easing);
     m_parent->updateSpecifiedTiming(timing);
 }
 
 void AnimationNodeTiming::trace(Visitor* visitor)
 {
     visitor->trace(m_parent);
 }
 
 } // namespace blink