some fixes for --strong warnings

lib/src/report.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.
 
 /// Summarizes the information produced by the checker.
 library dev_compiler.src.report;
 
 import 'dart:math' show max;
 
 import 'package:analyzer/src/generated/engine.dart' show AnalysisContext;
@@ skipping 186 matching lines @@
   /// Add a column with the given [name].
   void declareColumn(String name, {bool abbreviate: false}) {
     assert(!_sealed);
     var headerName = name;
     if (abbreviate) {
       // abbreviate the header by using only the capital initials.
       headerName = name.replaceAll(new RegExp('[a-z]'), '');
       while (abbreviations[headerName] != null) headerName = "$headerName'";
       abbreviations[headerName] = name;
     }
-    widths.add(max(5, headerName.length + 1));
+    widths.add(max(5, headerName.length + 1) as int);
     header.add(headerName);
     _totalColumns++;
   }
 
   /// Add an entry in the table, creating a new row each time [totalColumns]
   /// entries are added.
   void addEntry(entry) {
     if (_currentRow == null) {
       _sealed = true;
       _currentRow = [];
@@ skipping 93 matching lines @@
 
   visitMessage(MessageSummary message) {
     var kind = message.kind;
     errorCount.putIfAbsent(currentPackage, () => <String, int>{});
     errorCount[currentPackage].putIfAbsent(kind, () => 0);
     errorCount[currentPackage][kind]++;
     totals.putIfAbsent(kind, () => 0);
     totals[kind]++;
   }
 }