[Compose] Minor Perf fix on JsonConstraintSet

Properly tag when a JSONConstraintSet may have changed to update
ConstraintLayout's core State.

Previously, it would always cause the State to re-initialize which
implies parsing the string into a Json object and then iterating over
it. Causing a significant overhead when ConstraintLayout is part of an
animation.

constraintlayout/compose/src/main/java/androidx/constraintlayout/compose/ConstraintLayout.kt

@@ -738,7 +738,7 @@ internal abstract class EditableJSONLayout(@Language("json5") content: String) :
  }
 
  fun setCurrentContent(content: String) {
- currentContent = content
+ onNewContent(content)
  }
 
  fun getCurrentContent() : String{

constraintlayout/compose/src/main/java/androidx/constraintlayout/compose/JSONConstraintSet.kt

@@ -16,6 +16,7 @@
 
 package androidx.constraintlayout.compose
 
+import androidx.compose.ui.layout.Measurable
 import androidx.constraintlayout.core.parser.CLKey
 import androidx.constraintlayout.core.parser.CLParser
 import androidx.constraintlayout.core.parser.CLParsingException
@@ -31,6 +32,7 @@ internal class JSONConstraintSet(
 ) : EditableJSONLayout(content), DerivedConstraintSet {
  private val overridedVariables = HashMap<String, Float>()
  private val overrideVariables = overrideVariables
+ private var _isDirty = true
 
  init {
  initialization()
@@ -43,6 +45,10 @@ internal class JSONConstraintSet(
  return false
  }
 
+ override fun isDirty(measurables: List<Measurable>): Boolean {
+ return _isDirty
+ }
+
  // Only called by MotionLayout in MotionMeasurer
  override fun applyTo(transition: Transition, type: Int) {
  val layoutVariables = LayoutVariables()
@@ -66,11 +72,18 @@ internal class JSONConstraintSet(
  // TODO: Need to better handle half parsed JSON and/or incorrect states.
  try {
  parseJSON(getCurrentContent(), state, layoutVariables)
+ _isDirty = false
  } catch (e : Exception) {
  // nothing (content might be invalid, sent by live edit)
+ _isDirty = true
  }
  }
 
+ override fun onNewContent(content: String) {
+ super.onNewContent(content)
+ _isDirty = true
+ }
+
  override fun override(name: String, value: Float): ConstraintSet {
  overridedVariables[name] = value
  return this