Add hotReloadMillisecondsToFrameAfterChange benchmark. (#16406)

This fixes https://github.com/dart-lang/sdk/issues/32598.

dev/devicelab/lib/tasks/hot_mode_tests.dart

diff --git a/dev/devicelab/lib/tasks/hot_mode_tests.dart b/dev/devicelab/lib/tasks/hot_mode_tests.dart
index e82192c..32aeffb 100644
--- a/dev/devicelab/lib/tasks/hot_mode_tests.dart
+++ b/dev/devicelab/lib/tasks/hot_mode_tests.dart
@@ -142,6 +142,7 @@
         'hotReloadDevFSSyncMilliseconds': twoReloadsData['hotReloadDevFSSyncMilliseconds'][0],
         'hotReloadFlutterReassembleMilliseconds': twoReloadsData['hotReloadFlutterReassembleMilliseconds'][0],
         'hotReloadVMReloadMilliseconds': twoReloadsData['hotReloadVMReloadMilliseconds'][0],
+        'hotReloadMillisecondsToFrameAfterChange' : twoReloadsData['hotReloadMillisecondsToFrame'][1],
         'hotReloadDevFSSyncMillisecondsAfterChange': twoReloadsData['hotReloadDevFSSyncMilliseconds'][1],
         'hotReloadFlutterReassembleMillisecondsAfterChange': twoReloadsData['hotReloadFlutterReassembleMilliseconds'][1],
         'hotReloadVMReloadMillisecondsAfterChange': twoReloadsData['hotReloadVMReloadMilliseconds'][1],
@@ -154,6 +155,7 @@
         'hotReloadDevFSSyncMilliseconds',
         'hotReloadFlutterReassembleMilliseconds',
         'hotReloadVMReloadMilliseconds',
+        'hotReloadMillisecondsToFrameAfterChange',
         'hotReloadDevFSSyncMillisecondsAfterChange',
         'hotReloadFlutterReassembleMillisecondsAfterChange',
         'hotReloadVMReloadMillisecondsAfterChange',