Fix up MediaQuery's operator= and hashCode

packages/flutter/lib/src/widgets/binding.dart

@@ -62,7 +62,7 @@ class WidgetFlutterBinding extends BindingBase with Scheduler, Gesturer, Rendere
   void handleMetricsChanged() {
     super.handleMetricsChanged();
     for (BindingObserver observer in _observers)
-      observer.didChangeMetrics(ui.window.size);
+      observer.didChangeMetrics();
   }
 
   void handleLocaleChanged() {

packages/flutter/lib/src/widgets/media_query.dart

@@ -39,10 +39,15 @@ class MediaQueryData {
       return false;
     MediaQueryData typedOther = other;
     return typedOther.size == size
-        && typedOther.padding == padding;
+        && typedOther.padding == padding
+        && typedOther.devicePixelRatio == devicePixelRatio;
   }
 
-  int get hashCode => size.hashCode;
+  int get hashCode => hashValues(
+    size.hashCode,
+    padding.hashCode,
+    devicePixelRatio.hashCode
+  );
 
   String toString() => '$runtimeType($size, $orientation)';
 }