Revert "Fix SnackBar clipping when it is floating due to FloatingActionButton...

Revert "Fix SnackBar clipping when it is floating due to FloatingActionButton positioning (#47616)" (#50516)

This reverts commit 801a6a7e.

packages/flutter/lib/src/material/scaffold.dart

@@ -547,13 +547,9 @@ class _ScaffoldLayout extends MultiChildLayoutDelegate {
       if (snackBarSize == Size.zero) {
         snackBarSize = layoutChild(_ScaffoldSlot.snackBar, fullWidthConstraints);
       }
-
-      double snackBarYOffsetBase;
-      if (floatingActionButtonRect.size != Size.zero && isSnackBarFloating)
-        snackBarYOffsetBase = floatingActionButtonRect.top;
-      else
-        snackBarYOffsetBase = contentBottom;
-
+      final double snackBarYOffsetBase = floatingActionButtonRect != null && isSnackBarFloating
+        ? floatingActionButtonRect.top
+        : contentBottom;
       positionChild(_ScaffoldSlot.snackBar, Offset(0.0, snackBarYOffsetBase - snackBarSize.height));
     }