Add a microbenchmark for text intrinsic height layout (#145007)

For https://github.com/flutter/flutter/pull/144577. There's no promise that the performance will be great when `IntrinsicHeight/IntrinsicWidth` is used extensively but it's not that uncommon of a widget.

dev/benchmarks/microbenchmarks/lib/layout/text_intrinsic_bench.dart

@@ -0,0 +1,62 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import '../common.dart';
+
+const Duration kBenchmarkTime = Duration(seconds: 15);
+
+// Use an Align to loosen the constraints.
+final Widget intrinsicTextHeight = Align(
+  child: IntrinsicHeight(
+    child: Text('A' * 100),
+  ),
+);
+
+Future<void> main() async {
+  assert(false, "Don't run benchmarks in debug mode! Use 'flutter run --release'.");
+
+  // We control the framePolicy below to prevent us from scheduling frames in
+  // the engine, so that the engine does not interfere with our timings.
+  final LiveTestWidgetsFlutterBinding binding = TestWidgetsFlutterBinding.ensureInitialized() as LiveTestWidgetsFlutterBinding;
+
+  final Stopwatch watch = Stopwatch();
+  int iterations = 0;
+
+  await benchmarkWidgets((WidgetTester tester) async {
+    runApp(intrinsicTextHeight);
+
+    final TestViewConfiguration big = TestViewConfiguration.fromView(
+      size: const Size(360.0, 640.0),
+      view: tester.view,
+    );
+    final TestViewConfiguration small = TestViewConfiguration.fromView(
+      size: const Size(100.0, 640.0),
+      view: tester.view,
+    );
+    final RenderView renderView = WidgetsBinding.instance.renderViews.single;
+    binding.framePolicy = LiveTestWidgetsFlutterBindingFramePolicy.benchmark;
+
+    watch.start();
+    while (watch.elapsed < kBenchmarkTime) {
+      renderView.configuration = iterations.isEven ? big : small;
+      await tester.pumpBenchmark(Duration(milliseconds: iterations * 16));
+      iterations += 1;
+    }
+    watch.stop();
+  });
+
+
+  final BenchmarkResultPrinter printer = BenchmarkResultPrinter();
+  printer.addResult(
+    description: 'Text intrinsic height',
+    value: watch.elapsedMicroseconds / iterations,
+    unit: 'µs per iteration',
+    name: 'text_intrinsic_height_iteration',
+  );
+  printer.printToStdout();
+}

dev/devicelab/lib/tasks/microbenchmarks.dart

@@ -74,6 +74,7 @@ TaskFunction createMicrobenchmarkTask({
       ...await runMicrobench('lib/stocks/build_bench.dart'),
       ...await runMicrobench('lib/stocks/layout_bench.dart'),
       ...await runMicrobench('lib/ui/image_bench.dart'),
+      ...await runMicrobench('lib/layout/text_intrinsic_bench.dart'),
     };
 
     return TaskResult.success(allResults,