Fix errors and warnings

pkg/analysis_server/lib/src/status/get_handler.dart

 // Copyright (c) 2014, 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.
 
 library analysis_server.src.status.get_handler;
 
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io';
 import 'dart:math';
@@ skipping 2168 matching lines @@
               if (libraryElement.isInSdk) {
                 libraryElement.accept(sdkCounter);
               } else {
                 libraryElement.accept(counter);
               }
             }
           }
         }
         buffer.write('<p>element count: ');
         buffer.write(counter.counts.values
-            .fold(0, (int prev, int element) => prev + element));
+            .fold<int>(0, (int prev, int element) => prev + element));
         buffer.write('</p>');
         buffer.write('<p>  (w/docs): ');
         buffer.write(counter.elementsWithDocs);
         buffer.write('</p>');
         buffer.write('<p>total doc span: ');
         buffer.write(counter.totalDocSpan);
         buffer.write('</p>');
       }
     }
 
     buffer.write('<p><h3>');
     buffer.write('SDK');
     buffer.write('</h3></p>');
     buffer.write('<p>element count: ');
     buffer.write(sdkCounter.counts.values
-        .fold(0, (int prev, int element) => prev + element));
+        .fold<int>(0, (int prev, int element) => prev + element));
     buffer.write('</p>');
     buffer.write('<p>  (w/docs): ');
     buffer.write(sdkCounter.elementsWithDocs);
     buffer.write('</p>');
     buffer.write('<p>total doc span: ');
     buffer.write(sdkCounter.totalDocSpan);
     buffer.write('</p>');
   }
 
   /**
@@ skipping 532 matching lines @@
    */
   static String makeLink(
       String path, Map<String, String> params, String innerHtml,
       [bool hasError = false]) {
     Uri uri = new Uri(path: path, queryParameters: params);
     String href = HTML_ESCAPE.convert(uri.toString());
     String classAttribute = hasError ? ' class="error"' : '';
     return '<a href="$href"$classAttribute>$innerHtml</a>';
   }
 }