Turned on ImageFilter.compose for web CupertinoDesktopTextSelectionToolbar (#163229)

flutter/flutter#120123 was closed out so this
should work now.

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Author: gaaclarke

packages/flutter/lib/src/cupertino/desktop_text_selection_toolbar.dart

@@ -10,7 +10,6 @@ library;
 
 import 'dart:ui';
 
-import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 
 import 'colors.dart';
@@ -108,15 +107,10 @@ class CupertinoDesktopTextSelectionToolbar extends StatelessWidget {
         borderRadius: BorderRadius.all(_kToolbarBorderRadius),
       ),
       child: BackdropFilter(
-        // Flutter web doesn't support ImageFilter.compose on CanvasKit yet
-        // (https://github.com/flutter/flutter/issues/120123).
-        filter:
-            kIsWeb
-                ? ImageFilter.blur(sigmaX: _kToolbarBlurSigma, sigmaY: _kToolbarBlurSigma)
-                : ImageFilter.compose(
-                  outer: ColorFilter.matrix(_matrixWithSaturation(_kToolbarSaturationBoost)),
-                  inner: ImageFilter.blur(sigmaX: _kToolbarBlurSigma, sigmaY: _kToolbarBlurSigma),
-                ),
+        filter: ImageFilter.compose(
+          outer: ColorFilter.matrix(_matrixWithSaturation(_kToolbarSaturationBoost)),
+          inner: ImageFilter.blur(sigmaX: _kToolbarBlurSigma, sigmaY: _kToolbarBlurSigma),
+        ),
         child: DecoratedBox(
           decoration: BoxDecoration(
             color: _kToolbarBackgroundColor.resolveFrom(context),

packages/flutter/test/cupertino/desktop_text_selection_toolbar_test.dart

@@ -5,7 +5,6 @@
 import 'dart:ui';
 
 import 'package:flutter/cupertino.dart';
-import 'package:flutter/foundation.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
@@ -41,12 +40,7 @@ void main() {
       // for blur and saturation, but checking if it's a _ComposeImageFilter
       // should be enough. Outer and inner parameters don't matter, we just need
       // a new _ComposeImageFilter to get its runtimeType.
-      //
-      // As web doesn't support ImageFilter.compose, we use just blur when
-      // kIsWeb.
-      kIsWeb
-          ? ImageFilter.blur().runtimeType
-          : ImageFilter.compose(outer: ImageFilter.blur(), inner: ImageFilter.blur()).runtimeType,
+      ImageFilter.compose(outer: ImageFilter.blur(), inner: ImageFilter.blur()).runtimeType,
     );
   });