Revert "Cache computed window.physicalSize in a FrameReference (flutter#15955)"

This reverts commit 903f7c4.

Author: NoamDev

lib/web_ui/lib/src/engine/window.dart

@@ -47,24 +47,11 @@ class EngineWindow extends ui.Window {
 
   @override
   ui.Size get physicalSize {
-    if (_physicalSize?.value == null) {
-      _computePhysicalSize();
-    }
-    assert(_physicalSize != null);
-    assert(_physicalSize.value != null);
-    return _physicalSize.value;
-  }
-
-  /// Computes the physical size of the screen from [html.window].
-  ///
-  /// This function is expensive. It triggers browser layout if there are
-  /// pending DOM writes.
-  void _computePhysicalSize() {
     bool override = false;
 
     assert(() {
       if (webOnlyDebugPhysicalSizeOverride != null) {
-        _physicalSize = FrameReference<ui.Size>(webOnlyDebugPhysicalSizeOverride);
+        _physicalSize = webOnlyDebugPhysicalSizeOverride;
         override = true;
       }
       return true;
@@ -81,15 +68,23 @@ class EngineWindow extends ui.Window {
         windowInnerWidth = html.window.innerWidth * devicePixelRatio;
         windowInnerHeight = html.window.innerHeight * devicePixelRatio;
       }
-      _physicalSize = FrameReference<ui.Size>(ui.Size(
-        windowInnerWidth,
-        windowInnerHeight,
-      ));
+      if (windowInnerWidth != _lastKnownWindowInnerWidth ||
+          windowInnerHeight != _lastKnownWindowInnerHeight) {
+        _lastKnownWindowInnerWidth = windowInnerWidth;
+        _lastKnownWindowInnerHeight = windowInnerHeight;
+        _physicalSize = ui.Size(
+          windowInnerWidth,
+          windowInnerHeight,
+        );
+      }
     }
+
+    return _physicalSize;
   }
 
-  /// Lazily populated and cleared at the end of the frame.
-  FrameReference<ui.Size> _physicalSize;
+  ui.Size _physicalSize = ui.Size.zero;
+  double _lastKnownWindowInnerWidth = -1;
+  double _lastKnownWindowInnerHeight = -1;
 
   /// Overrides the value of [physicalSize] in tests.
   ui.Size webOnlyDebugPhysicalSizeOverride;