Revert "[cfe] Run suite in together in update_expectations.dart"

This reverts commit 1f109d10ec07f34e3457c3377f47ebfdad20eed2.

Reason for revert: This interferes (weirdly) with which expectation files are being generated.

Original change's description:
> [cfe] Run suite in together in update_expectations.dart
>
> This speeds up update_expectations.dart by avoid to restart
> the expectation testing for each suite.
>
> Change-Id: Idaeb1cff3ac861b6d4781a4166442a102c754c71
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/342586
> Commit-Queue: Johnni Winther <johnniwinther@google.com>
> Reviewed-by: Jens Johansen <jensj@google.com>

Change-Id: I807ab0dab9e7349bb09350a788f59d2ae7156804
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/342840
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Chloe Stefantsova <cstefantsova@google.com>
Commit-Queue: Johnni Winther <johnniwinther@google.com>
diff --git a/pkg/front_end/tool/update_expectations.dart b/pkg/front_end/tool/update_expectations.dart
index 0c0c448..bed85ca 100644
--- a/pkg/front_end/tool/update_expectations.dart
+++ b/pkg/front_end/tool/update_expectations.dart
@@ -21,23 +21,22 @@
 Future<void> runStandardSuites([List<String>? args]) async {
   // Assert that 'strong' is the first suite - we use the assumption below.
   assert(standardSuites.first == 'weak', "Suite 'weak' most be the first.");
-
-  List<String> testingArguments = [];
+  bool first = true;
   for (String suite in standardSuites) {
     List<String> tests = args == null
         ? [suite]
         : args.map((String arg) => '${suite}/$arg').toList();
-    testingArguments.addAll(tests);
+    await fasta.main([
+      'testing',
+      ...tests,
+      // Only update comments in the first suite. Note that this only works
+      // if the first compilation is a full compilation, i.e. not outline,
+      // because comments are generated during body building and inference.
+      if (first) '-DupdateComments=true',
+      '-DupdateExpectations=true'
+    ]);
+    first = false;
   }
-  await fasta.main([
-    'testing',
-    ...testingArguments,
-    // Only update comments in the first suite. Note that this only works
-    // if the first compilation is a full compilation, i.e. not outline,
-    // because comments are generated during body building and inference.
-    '-DupdateComments=true',
-    '-DupdateExpectations=true'
-  ]);
 }
 
 Future<void> main(List<String> args) async {
@@ -62,7 +61,7 @@
       }
     }
     if (standardTests.isNotEmpty) {
-      await runStandardSuites(standardTests);
+      await runStandardSuites(args);
     }
   }
 }