Mark analysis_server as being strong-mode clean

pkg/analysis_server/lib/src/source/caching_pub_package_map_provider.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.
 
 library source.caching_pub_package_map_provider;
 
 import 'dart:convert';
 import 'dart:core' hide Resource;
 import 'dart:io' as io;
 
@@ skipping 88 matching lines @@
     // cached result because folder may be only temporarily inaccessible
     //
     if (!folder.exists) {
       return computePackageMapError(folder);
     }
     // Ensure cache is up to date
     _readCache();
     // Check for cached entry
     Map entry = _cache[folder.path];
     if (entry != null) {
-      Map<String, int> modificationStamps = entry[modificationStampsKey];
+      Map<String, int> modificationStamps =
+          entry[modificationStampsKey] as Map<String, int>;
       if (modificationStamps != null) {
         //
         // Check to see if any dependencies have changed
         // before returning cached result
         //
         if (!_haveDependenciesChanged(modificationStamps)) {
           return parsePackageMap(entry[pubListResultKey], folder);
         }
       }
     }
@@ skipping 90 matching lines @@
     // TODO(danrubel) This implementation assumes that
     // two separate processes are not accessing the cache file at the same time
     Source source = cacheFile.createSource();
     if (source.exists() &&
         (_cache == null ||
             _cacheModificationTime != source.modificationStamp)) {
       try {
         TimestampedData<String> data = source.contents;
         Map map = JSON.decode(data.data);
         if (map[cacheVersionKey] == cacheVersion) {
-          _cache = map[cacheKey];
+          _cache = map[cacheKey] as Map<String, Map>;
           _cacheModificationTime = data.modificationTime;
         }
       } catch (exception, stackTrace) {
         AnalysisEngine.instance.logger.logInformation(
             'Exception reading $cacheFile\n$exception\n$stackTrace');
       }
     }
     if (_cache == null) {
       _cache = new Map<String, Map>();
     }
@@ skipping 19 matching lines @@
     // TODO(danrubel) This implementation assumes that
     // two separate processes are not accessing the cache file at the same time
     io.File file = new io.File(cacheFile.path);
     if (!file.parent.existsSync()) {
       file.parent.createSync(recursive: true);
     }
     file.writeAsStringSync(content, flush: true);
     return file.lastModifiedSync().millisecondsSinceEpoch;
   }
 }