Bug 1080909 - Do not accept a zero time constant when calling AudioParam.setTargetAtTime in order to avoid the division by zero later on; r=padenot

content/media/webaudio/AudioEventTimeline.h

@@ -15,6 +15,7 @@
 
 #include "nsTArray.h"
 #include "math.h"
+#include "WebAudioUtils.h"
 
 namespace mozilla {
 
@@ -75,6 +76,11 @@ struct AudioTimelineEvent {
       }
     }
 
+    if (mType == AudioTimelineEvent::SetTarget &&
+        WebAudioUtils::FuzzyEqual(mTimeConstant, 0.0)) {
+      return false;
+    }
+
     return IsValid(mTime) &&
            IsValid(mValue) &&
            IsValid(mTimeConstant) &&

content/media/webaudio/compiledtest/TestAudioEventTimeline.cpp

@@ -391,7 +391,7 @@ void TestSetTargetZeroTimeConstant()
   ErrorResultMock rv;
 
   timeline.SetTargetAtTime(20.0f, 1.0, 0.0, rv);
-  is(timeline.GetValueAtTime(10.), 20.f, "Should get the correct value with timeConstant == 0");
+  is(rv, NS_ERROR_DOM_SYNTAX_ERR, "Correct error code returned");
 }
 
 void TestExponentialInvalidPreviousZeroValue()