Change HashMap declarations back to Map.

pkg/analysis_server/lib/src/resource.dart

Index: pkg/analysis_server/lib/src/resource.dart
diff --git a/pkg/analysis_server/lib/src/resource.dart b/pkg/analysis_server/lib/src/resource.dart
index 87b67fb54e2364eef9c19d61ae5b2e789331fa62..58a726f3866607161d8f37eb7285173f8b9e68c6 100644
--- a/pkg/analysis_server/lib/src/resource.dart
+++ b/pkg/analysis_server/lib/src/resource.dart
@@ -306,11 +306,11 @@ class _MemoryFolder extends _MemoryResource implements Folder {
  * Use `/` as a path separator.
  */
 class MemoryResourceProvider implements ResourceProvider {
-  final HashMap<String, _MemoryResource> _pathToResource =
+  final Map<String, _MemoryResource> _pathToResource =
       new HashMap<String, _MemoryResource>();
-  final HashMap<String, String> _pathToContent = new HashMap<String, String>();
-  final HashMap<String, int> _pathToTimestamp = new HashMap<String, int>();
-  final HashMap<String, List<StreamController<WatchEvent>>> _pathToWatchers =
+  final Map<String, String> _pathToContent = new HashMap<String, String>();
+  final Map<String, int> _pathToTimestamp = new HashMap<String, int>();
+  final Map<String, List<StreamController<WatchEvent>>> _pathToWatchers =
       new HashMap<String, List<StreamController<WatchEvent>>>();
   int nextStamp = 0;