[benchmarks] Use gen_kernel instead of dart2js for isolate group benchmarks.

- dart2js does not run in NNBD but gen_kernel does.
 - Changes to dart2js to not trigger VM benchmarks to run on Golem, allowing performance differences to accumulate until the next unrelated VM change. Changes to the front end or package:vm cause a binary diff in the platform file or kernel-service snapshot and so do trigger VM benchmarks to run on Golem.
 - These benchmarks don't care about running dart2js in particular, just some large program.

Change-Id: I85e339c32edbf9d0261081623378475fa0b9507a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/270022
Reviewed-by: Siva Annamalai <asiva@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Jonas Termansen <sortie@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>

benchmarks/IsolateSpawn/dart/IsolateSpawn.dart

@@ -6,7 +6,7 @@ import 'dart:async';
 import 'dart:isolate';
 import 'dart:math';
 
-import 'package:compiler/src/dart2js.dart' as dart2js_main;
+import '../../../pkg/vm/bin/gen_kernel.dart' as gen_kernel;
 
 class SpawnLatency {
   SpawnLatency(this.name);
@@ -144,9 +144,9 @@ $toExitUs''';
 Future<void> isolateCompiler(StartMessageLatency start) async {
   final timeRunningCodeUs = DateTime.now();
   await runZoned(
-      () => dart2js_main.internalMain(<String>[
+      () => gen_kernel.compile(<String>[
             'benchmarks/IsolateSpawn/dart/helloworld.dart',
-            '--libraries-spec=sdk/lib/libraries.json'
+            'benchmarks/IsolateSpawn/dart/helloworld.dart.dill',
           ]),
       zoneSpecification: ZoneSpecification(
           print: (Zone self, ZoneDelegate parent, Zone zone, String line) {}));

benchmarks/IsolateSpawnMemory/dart/IsolateSpawnMemory.dart

@@ -8,7 +8,7 @@ import 'dart:io';
 import 'dart:isolate';
 import 'dart:math' as math;
 
-import 'package:compiler/src/dart2js.dart' as dart2js_main;
+import '../../../pkg/vm/bin/gen_kernel.dart' as gen_kernel;
 import 'package:vm_service/vm_service.dart' as vm_service;
 import 'package:vm_service/vm_service_io.dart' as vm_service_io;
 
@@ -65,7 +65,7 @@ class SpawnMemory {
     final readyRss = ProcessInfo.currentRss;
     final readyHeap = await currentHeapUsage(wsUri);
 
-    // Let all isolates do the dart2js compilation.
+    // Let all isolates do the gen_kernel compilation.
     for (int i = 0; i < numberOfBenchmarks; i++) {
       final iterator = iterators[i];
       final continuation = continuations[i];
@@ -116,9 +116,9 @@ Future<void> isolateCompiler(StartMessage startMessage) async {
   await iterator.moveNext();
 
   await runZoned(
-      () => dart2js_main.internalMain(<String>[
-            'benchmarks/IsolateSpawnMemory/dart/helloworld.dart',
-            '--libraries-spec=sdk/lib/libraries.json'
+      () => gen_kernel.compile(<String>[
+            'benchmarks/IsolateSpawn/dart/helloworld.dart',
+            'benchmarks/IsolateSpawn/dart/helloworld.dart.dill',
           ]),
       zoneSpecification: ZoneSpecification(
           print: (Zone self, ZoneDelegate parent, Zone zone, String line) {}));
@@ -138,7 +138,7 @@ Future<int> currentHeapUsage(String wsUri) async {
   int sum = 0;
   for (final groupId in groupIds) {
     final usage = await vmService.getIsolateGroupMemoryUsage(groupId);
-    sum += usage.heapUsage + usage.externalUsage;
+    sum += usage.heapUsage! + usage.externalUsage!;
   }
   vmService.dispose();
   return sum;
@@ -161,12 +161,12 @@ Future<void> main() async {
 Future<List<String>> getGroupIds(vm_service.VmService vmService) async {
   final groupIds = <String>{};
   final vm = await vmService.getVM();
-  for (final groupRef in vm.isolateGroups) {
-    final group = await vmService.getIsolateGroup(groupRef.id);
-    for (final isolateRef in group.isolates) {
-      final isolateOrSentinel = await vmService.getIsolate(isolateRef.id);
+  for (final groupRef in vm.isolateGroups!) {
+    final group = await vmService.getIsolateGroup(groupRef.id!);
+    for (final isolateRef in group.isolates!) {
+      final isolateOrSentinel = await vmService.getIsolate(isolateRef.id!);
       if (isolateOrSentinel is vm_service.Isolate) {
-        groupIds.add(groupRef.id);
+        groupIds.add(groupRef.id!);
       }
     }
   }

benchmarks/Startup/dart/Startup.dart

@@ -5,7 +5,7 @@
 import 'dart:convert';
 import 'dart:io';
 
-import 'package:compiler/src/dart2js.dart' as dart2js;
+import '../../../pkg/vm/bin/gen_kernel.dart' as gen_kernel;
 
 Future<void> main(List<String> args) async {
   if (args.contains('--child')) {
@@ -16,7 +16,7 @@ Future<void> main(List<String> args) async {
   // non-trival snapshot size.
   if (args.contains('--train')) {
     args.remove('--train');
-    return dart2js.main(args);
+    return gen_kernel.main(args);
   }
 
   var tempDir;
@@ -54,7 +54,7 @@ Future<void> main(List<String> args) async {
     throw 'Could not determine main isolate';
   }
 
-  void report(String name, String isolateId) {
+  void report(String name, String? isolateId) {
     var filtered = events.where((event) => event['name'] == name);
     if (isolateId != null) {
       filtered =