[dynamic_layouts] relax layout test to fix tree (flutter#4677)

A current roll from the engine to flutter/flutter to packages has broken this test value by a small amount. 

I wrote a small function to manage tolerances.

Let me know if this is a reasonable way to manage this for now.

Author: tarrinneal

.ci/flutter_master.version

@@ -1 +1 @@
-f4c25bbb351cc59ffdefe980c0c993196a8a6d47
+685141bf3b5ff4a90589fd77784776e011dd5fcc

packages/dynamic_layouts/example/test/wrap_example_test.dart

@@ -3,11 +3,33 @@
 // found in the LICENSE file.
 
 import 'package:example/wrap_layout_example.dart';
-import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
+  void withinTolerance(Offset actual, Offset expected, double tolerance) {
+    expect(
+      actual.dx,
+      (double actual) => actual <= expected.dx + tolerance,
+      reason: '${actual.dx} <= ${expected.dx + tolerance}',
+    );
+    expect(
+      actual.dx,
+      (double actual) => actual >= expected.dx - tolerance,
+      reason: '${actual.dx} >= ${expected.dx - tolerance}',
+    );
+    expect(
+      actual.dy,
+      (double actual) => actual <= expected.dy + tolerance,
+      reason: '${actual.dy} <= ${expected.dy + tolerance}',
+    );
+    expect(
+      actual.dy,
+      (double actual) => actual >= expected.dy - tolerance,
+      reason: '${actual.dy} >= ${expected.dy - tolerance}',
+    );
+  }
+
   testWidgets('Check that the children are layed out.',
       (WidgetTester tester) async {
     const MaterialApp app = MaterialApp(
@@ -25,27 +47,19 @@ void main() {
 
     // Material 3 changes the expected layout positioning.
     final bool usesMaterial3 = (app.theme ?? ThemeData.light()).useMaterial3;
-    final Offset offset0 = usesMaterial3
-        ? Offset(0.0, _getExpectedYOffset(91.0))
-        : const Offset(0.0, 103.0);
-    final Offset offset1 = usesMaterial3
-        ? Offset(65.0, _getExpectedYOffset(121.0))
-        : const Offset(66.0, 124.0);
-    final Offset offset3 = usesMaterial3
-        ? Offset(270.0, _getExpectedYOffset(171.0))
-        : const Offset(271.0, 174.0);
-    final Offset offset4 = usesMaterial3
-        ? Offset(380.0, _getExpectedYOffset(221.0))
-        : const Offset(381.0, 224.0);
+    final Offset offset0 =
+        usesMaterial3 ? const Offset(0.0, 91.0) : const Offset(0.0, 103.0);
+    final Offset offset1 =
+        usesMaterial3 ? const Offset(65.0, 121.0) : const Offset(66.0, 124.0);
+    final Offset offset3 =
+        usesMaterial3 ? const Offset(270.0, 171.0) : const Offset(271.0, 174.0);
+    final Offset offset4 =
+        usesMaterial3 ? const Offset(380.0, 221.0) : const Offset(381.0, 224.0);
 
     // See if they are in expected position.
-    expect(tester.getTopLeft(find.text('Index 0')), offset0);
-    expect(tester.getTopLeft(find.text('Index 1')), offset1);
-    expect(tester.getTopLeft(find.text('Index 3')), offset3);
-    expect(tester.getTopLeft(find.text('Index 4')), offset4);
+    withinTolerance(tester.getTopLeft(find.text('Index 0')), offset0, 0.2);
+    withinTolerance(tester.getTopLeft(find.text('Index 1')), offset1, 0.2);
+    withinTolerance(tester.getTopLeft(find.text('Index 3')), offset3, 0.2);
+    withinTolerance(tester.getTopLeft(find.text('Index 4')), offset4, 0.2);
   });
 }
-
-double _getExpectedYOffset(double nonWeb) {
-  return kIsWeb ? nonWeb - 0.5 : nonWeb;
-}