Redo our benchmarks; add a benchmark/benchmarks.dart tool.

pkg/analysis_server/benchmark/perf/completion_timing_tests.dart

Index: pkg/analysis_server/benchmark/perf/completion_timing_tests.dart
diff --git a/pkg/analysis_server/benchmark/perf/completion_timing_tests.dart b/pkg/analysis_server/benchmark/perf/completion_timing_tests.dart
index 6acd038f3581f7d82b56bac2d69e80f811ebddbf..0a1204195b9adc52dfbf1f01ee6cd5aaf175716e 100644
--- a/pkg/analysis_server/benchmark/perf/completion_timing_tests.dart
+++ b/pkg/analysis_server/benchmark/perf/completion_timing_tests.dart
@@ -10,32 +10,31 @@ import 'package:test/test.dart';
 
 import 'performance_tests.dart';
 
+const COMPLETION_OFFSET = 'offset';
+const PRIORITY_FILE_OPTION = 'priority';
+const SOURCE_OPTION = 'source';
+
 /**
  * Pass in the directory of the source to be analyzed as option `--source`,
  * specify a priority file with `--priority` and an offset for completions
  * with a `--offset`.
  */
-main(List<String> arguments) {
+main(List<String> arguments) async {
   ArgParser parser = _createArgParser();
   var args = parser.parse(arguments);
   if (args[SOURCE_OPTION] == null) {
     print('path to source directory must be specified');
     exit(1);
   }
-  source = args[SOURCE_OPTION];
-  priorityFile = args[PRIORITY_FILE_OPTION];
-  offset = int.parse(args[COMPLETION_OFFSET]);
-
-  Future.wait([new CompletionTimingTest().test_timing()]);
-}
 
-const COMPLETION_OFFSET = 'offset';
-const PRIORITY_FILE_OPTION = 'priority';
-const SOURCE_OPTION = 'source';
+  int offset = int.parse(args[COMPLETION_OFFSET]);
+  String priorityFile = args[PRIORITY_FILE_OPTION];
+  String source = args[SOURCE_OPTION];
 
-int offset;
-String priorityFile;
-String source;
+  CompletionTimingTest test =
+      new CompletionTimingTest(offset, priorityFile, source);
+  await test.test_timing();
+}
 
 ArgParser _createArgParser() => new ArgParser()
   ..addOption(SOURCE_OPTION, help: 'full path to source directory for analysis')
@@ -50,8 +49,14 @@ ArgParser _createArgParser() => new ArgParser()
  * completions.
  */
 class CompletionTimingTest extends AbstractTimingTest {
+  final int offset;
+  final String priorityFile;
+  final String source;
+
   List<Duration> timings = <Duration>[];
 
+  CompletionTimingTest(this.offset, this.priorityFile, this.source);
+
   Future test_timing() async {
 //    debugStdio();