Tighten up a bunch of types in test.dart.

tools/testing/dart/status_reporter.dart

 // Copyright (c) 2015, 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:io';
 import 'dart:convert';
 
-List<Map> LINUX_COMBINATIONS = [
+final LINUX_COMBINATIONS = [
   {
     'runtimes': ['none'],
     'modes': ['release'],
     'archs': ['x64'],
     'compiler': 'dart2analyzer'
   },
   {
     'runtimes': ['vm'],
     'modes': ['debug', 'release'],
     'archs': ['ia32', 'x64', 'simarm', 'simmips'],
@@ skipping 12 matching lines @@
     'compiler': 'none'
   },
   {
     'runtimes': ['flutter_engine'],
     'modes': ['debug', 'release'],
     'archs': ['x64'],
     'compiler': 'none'
   },
 ];
 
-List<Map> MACOS_COMBINATIONS = [
+final MACOS_COMBINATIONS = [
   {
     'runtimes': ['vm'],
     'modes': ['debug', 'release'],
     'archs': ['ia32', 'x64'],
     'compiler': 'none'
   },
   {
     'runtimes': ['safari', 'safarimobilesim'],
     'modes': ['release'],
     'archs': ['ia32'],
     'compiler': 'dart2js'
   },
   {
     'runtimes': ['dartium'],
     'modes': ['release', 'debug'],
     'archs': ['ia32'],
     'compiler': 'none'
   },
 ];
 
-List<Map> WINDOWS_COMBINATIONS = [
+final WINDOWS_COMBINATIONS = [
   {
     'runtimes': ['vm'],
     'modes': ['debug', 'release'],
     'archs': ['ia32', 'x64'],
     'compiler': 'none'
   },
   {
     'runtimes': ['chrome', 'ff', 'ie11', 'ie10'],
     'modes': ['release'],
     'archs': ['ia32'],
     'compiler': 'dart2js'
   },
   {
     'runtimes': ['dartium'],
     'modes': ['release', 'debug'],
     'archs': ['ia32'],
     'compiler': 'none'
   },
 ];
 
-Map<String, List<Map>> COMBINATIONS = {
+final COMBINATIONS = {
   'linux': LINUX_COMBINATIONS,
   'windows': WINDOWS_COMBINATIONS,
   'macos': MACOS_COMBINATIONS
 };
 
 List<Map> getCombinations() {
   return COMBINATIONS[Platform.operatingSystem];
 }
 
 void ensureBuild(Iterable<String> modes, Iterable<String> archs) {
@@ skipping 92 matching lines @@
             print(result.stderr);
             throw new Exception("Error running: ${args.join(" ")}");
           }
 
           // Find "JSON:"
           // Everything after will the JSON-formatted output
           // per --report-in-json flag above
           var totalIndex = result.stdout.indexOf('JSON:');
           var report = result.stdout.substring(totalIndex + 5);
 
-          var map = JSON.decode(report) as Map;
+          var map = JSON.decode(report) as Map<String, int>;
 
           if (keys == null) {
             keys = map.keys.toList();
             var firstKey = keys.removeAt(0);
             if (firstKey != 'total') {
               throw '"total" should be the first key';
             }
 
             var headers = ['compiler', 'runtime', 'arch', 'mode', 'total'];
             for (var k in keys) {
@@ skipping 11 matching lines @@
             var pct = 100 * (value / total);
             values.add('${pct.toStringAsFixed(3)}%');
           }
 
           print(values.join(','));
         }
       }
     }
   }
 }