Fix LayoutCoordinates reference leaks in #101

backdrop/src/commonMain/kotlin/com/kyant/backdrop/DrawBackdropModifier.kt

@@ -176,7 +176,10 @@ private class DrawBackdropElement(
         node.shapeProvider = shapeProvider
         node.effects = effects
         node.layerBlock = layerBlock
-        node.exportedBackdrop = exportedBackdrop
+        if (node.exportedBackdrop != exportedBackdrop) {
+            node.exportedBackdrop?.layerCoordinates = null
+            node.exportedBackdrop = exportedBackdrop
+        }
         node.onDrawBehind = onDrawBehind
         node.onDrawBackdrop = onDrawBackdrop
         node.onDrawSurface = onDrawSurface

backdrop/src/commonMain/kotlin/com/kyant/backdrop/backdrops/LayerBackdropModifier.kt

@@ -22,7 +22,10 @@ private class LayerBackdropElement(
     }
 
     override fun update(node: LayerBackdropNode) {
-        node.backdrop = backdrop
+        if (node.backdrop != backdrop) {
+            node.backdrop.layerCoordinates = null
+            node.backdrop = backdrop
+        }
         node.invalidateDraw()
     }