Fix #2071: cancelScheduledValues with setValueCurveAtTime (#2109)

If the cancelTime overlaps the setValueCurveAtTime event, remove the
event too.

index.bs

@@ -3617,6 +3617,12 @@ Methods</h4>
 		are also removed if the hold time occurs after
 		{{AudioParam/cancelScheduledValues()/cancelTime!!argument}}.
 
+		For a {{AudioParam/setValueCurveAtTime()}}, let \(T_0\) and \(T_D\) be the corresponding 
+		{{AudioParam/setValueCurveAtTime()/startTime!!argument}} and {{AudioParam/setValueCurveAtTime()/duration!!argument}}, respectively of this event.
+		Then if {{AudioParam/cancelScheduledValues()/cancelTime!!argument}}
+		is in the range \([T_0, T_0 + T_D]\), the event is
+		removed from the timeline.
+
 		<pre class=argumentdef for="AudioParam/cancelScheduledValues()">
 			cancelTime: The time after which any previously scheduled parameter changes will be cancelled. It is a time in the same time coordinate system as the {{AudioContext}}'s {{BaseAudioContext/currentTime}} attribute. <span class="synchronous">A {{RangeError}} exception MUST be thrown if <code>cancelTime</code> is negative or is not a finite number.</span> If <code>cancelTime</code> is less than {{BaseAudioContext/currentTime}}, it is clamped to {{BaseAudioContext/currentTime}}.
 		</pre>