Fix the wrong layout update on iOS10

On iOS 10, there is a case when a floating panel is updated by a
different position(the previous position) from the target position in
animating. This is because `FloatingPanelController` calls
`update(safeAreaInsets:)` in `viewDidLayoutSubviews()` unexpectedly.

Framework/Sources/FloatingPanel.swift

@@ -45,6 +45,7 @@ class FloatingPanel: NSObject, UIGestureRecognizerDelegate, UIScrollViewDelegate
     private var transOffsetY: CGFloat = 0
 
     var interactionInProgress: Bool = false
+    var isDecelerating: Bool = false
 
     // Scroll handling
     private var stopScrollDeceleration: Bool = false
@@ -520,6 +521,9 @@ class FloatingPanel: NSObject, UIGestureRecognizerDelegate, UIScrollViewDelegate
     private func startAnimation(to targetPosition: FloatingPanelPosition, at distance: CGFloat, with velocity: CGPoint) {
         log.debug("startAnimation", targetPosition, distance, velocity)
         let targetY = layoutAdapter.positionY(for: targetPosition)
+
+        isDecelerating = true
+
         let velocityVector = (distance != 0) ? CGVector(dx: 0, dy: max(min(velocity.y/distance, 30.0), -30.0)) : .zero
         let animator = behavior.interactionAnimator(self.viewcontroller, to: targetPosition, with: velocityVector)
         animator.addAnimations { [weak self] in
@@ -534,6 +538,7 @@ class FloatingPanel: NSObject, UIGestureRecognizerDelegate, UIScrollViewDelegate
         }
         animator.addCompletion { [weak self] pos in
             guard let `self` = self else { return }
+            self.isDecelerating = false
             guard
                 self.interactionInProgress == false,
                 animator == self.animator,

Framework/Sources/FloatingPanelController.swift

@@ -236,8 +236,9 @@ public class FloatingPanelController: UIViewController, UIScrollViewDelegate, UI
         // Don't re-layout the surface on SafeArea.Bottom enabled/disabled in interaction progress
         guard
             floatingPanel.layoutAdapter.safeAreaInsets != safeAreaInsets,
-            self.floatingPanel.interactionInProgress == false
-        else { return }
+            self.floatingPanel.interactionInProgress == false,
+            self.floatingPanel.isDecelerating == false
+            else { return }
 
         log.debug("Update safeAreaInsets", safeAreaInsets)