Turn on unawaited_futures in flutter_tools (#21048)

diff --git a/packages/flutter_tools/test/emulator_test.dart b/packages/flutter_tools/test/emulator_test.dart
index ffdc7a7..64f04e2 100644
--- a/packages/flutter_tools/test/emulator_test.dart
+++ b/packages/flutter_tools/test/emulator_test.dart
@@ -62,12 +62,12 @@
         expect(await testEmulatorManager.getEmulatorsMatching(id), expected);
       }
 
-      expectEmulator('Nexus_5', <Emulator>[emulator1]);
-      expectEmulator('Nexus_5X', <Emulator>[emulator2]);
-      expectEmulator('Nexus_5X_API_27_x86', <Emulator>[emulator2]);
-      expectEmulator('Nexus', <Emulator>[emulator1, emulator2]);
-      expectEmulator('iOS Simulator', <Emulator>[emulator3]);
-      expectEmulator('ios', <Emulator>[emulator3]);
+      await expectEmulator('Nexus_5', <Emulator>[emulator1]);
+      await expectEmulator('Nexus_5X', <Emulator>[emulator2]);
+      await expectEmulator('Nexus_5X_API_27_x86', <Emulator>[emulator2]);
+      await expectEmulator('Nexus', <Emulator>[emulator1, emulator2]);
+      await expectEmulator('iOS Simulator', <Emulator>[emulator3]);
+      await expectEmulator('ios', <Emulator>[emulator3]);
     });
 
     testUsingContext('create emulator with an empty name does not fail',