Fairly partition work in tools/full-coverage.dart.

tools/full-coverage.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import "dart:async";
 import "dart:convert";
 import "dart:io";
 import "dart:isolate";
 
 import "package:args/args.dart";
@@ skipping 253 matching lines @@
   files.forEach((File fileEntry) {
     // Read file sync, as it only contains 1 object.
     String contents = fileEntry.readAsStringSync();
     if (contents.length > 0) {
       mergeHitmaps(createHitmap(contents, resolver), workerHitmap);
     }
   });
 
   if (env["verbose"]) {
     final end = new DateTime.now().millisecondsSinceEpoch;
-    print("${msg.workerName}: Finished processing files. "
+    print("${msg.workerName}: Finished processing ${files.length} files. "
           "Took ${end - start} ms.");
   }
 
   msg.replyPort.send(new ResultMessage(workerHitmap, resolver.failed));
 }
 
 class WorkMessage {
   final String workerName;
   final Map environment;
   final List files;
   final SendPort replyPort;
   WorkMessage(this.workerName, this.environment, this.files, this.replyPort);
 }
 
 class ResultMessage {
   final hitmap;
   final failedResolves;
   ResultMessage(this.hitmap, this.failedResolves);
 }
 
 final env = new Environment();
 
 List<List> split(List list, int nBuckets) {
-  // Leftover goes in the last bucket.
-  // TODO(16505): Do a fair split.
   var buckets = new List(nBuckets);
   var bucketSize = list.length ~/ nBuckets;
+  var leftover = list.length % nBuckets;
   var taken = 0;
+  var start = 0;
   for (int i = 0; i < nBuckets; i++) {
-    bool lastBucket = i + 1 == nBuckets;
-    var start = i * bucketSize;
-    var end = lastBucket ? list.length : start + bucketSize ;
+    var end = (i < leftover) ? (start + bucketSize + 1) : (start + bucketSize);
     buckets[i] = list.sublist(start, end);
     taken += buckets[i].length;
+    start = end;
   }
   if (taken != list.length) throw "Error splitting";
   return buckets;
 }
 
 Future<ResultMessage> spawnWorker(name, environment, files) {
   RawReceivePort port = new RawReceivePort();
   var completer = new Completer();
   port.handler = ((ResultMessage msg) {
     completer.complete(msg);
@@ skipping 175 matching lines @@
   }
 
   try {
     env.workers = int.parse("${args["workers"]}");
   } catch (e) {
     fail("Invalid worker count: $e");
   }
 
   env.verbose = args["verbose"];
 }