Remove computeValue.isSpecified

This CL removes the isSpecified lambda from Element.computeValue. This
is not necessary anymore since http://aosp/2978852, which was pulled to
our prebuilts in http://ag/26476625.

Bug: 316901148
Test: atest PlatformComposeSceneTransitionLayoutTests
Flag: N/A
Change-Id: I668ee3694f17d610f5e151e560aa2012bd73d618

packages/SystemUI/compose/scene/src/com/android/compose/animation/scene/Element.kt

@@ -388,7 +388,6 @@ private fun elementAlpha(
             transformation = { it.alpha },
             idleValue = 1f,
             currentValue = { 1f },
-            isSpecified = { true },
             ::lerp,
         )
         .fastCoerceIn(0f, 1f)
@@ -426,7 +425,6 @@ private fun ApproachMeasureScope.measure(
             transformation = { it.size },
             idleValue = lookaheadSize,
             currentValue = { measurable.measure(constraints).also { maybePlaceable = it }.size() },
-            isSpecified = { it != Element.SizeUnspecified },
             ::lerp,
         )
 
@@ -452,7 +450,6 @@ private fun getDrawScale(
         transformation = { it.drawScale },
         idleValue = Scale.Default,
         currentValue = { Scale.Default },
-        isSpecified = { true },
         ::lerp,
     )
 }
@@ -493,7 +490,6 @@ private fun ApproachMeasureScope.place(
                 transformation = { it.offset },
                 idleValue = targetOffsetInScene,
                 currentValue = { currentOffset },
-                isSpecified = { it != Offset.Unspecified },
                 ::lerp,
             )
 
@@ -540,7 +536,6 @@ private inline fun <T> computeValue(
     transformation: (ElementTransformations) -> PropertyTransformation<T>?,
     idleValue: T,
     currentValue: () -> T,
-    isSpecified: (T) -> Boolean,
     lerp: (T, T, Float) -> T,
 ): T {
     val transition =
@@ -605,11 +600,6 @@ private inline fun <T> computeValue(
         val start = sceneValue(fromState!!)
         val end = sceneValue(toState!!)
 
-        // TODO(b/316901148): Remove checks to isSpecified() once the lookahead pass runs for all
-        // nodes before the intermediate layout pass.
-        if (!isSpecified(start)) return end
-        if (!isSpecified(end)) return start
-
         // Make sure we don't read progress if values are the same and we don't need to interpolate,
         // so we don't invalidate the phase where this is read.
         return if (start == end) start else lerp(start, end, transition.progress)