Change HashMap declarations back to Map.

pkg/analysis_server/lib/src/computer/element.dart

Index: pkg/analysis_server/lib/src/computer/element.dart
diff --git a/pkg/analysis_server/lib/src/computer/element.dart b/pkg/analysis_server/lib/src/computer/element.dart
index 3be6112642d5b08d3e9c248763f053497d7d0e1d..9b23a7504779d4f58194d7d06f9011f1d89ccb6a 100644
--- a/pkg/analysis_server/lib/src/computer/element.dart
+++ b/pkg/analysis_server/lib/src/computer/element.dart
@@ -4,8 +4,6 @@
 
 library computer.element;
 
-import 'dart:collection';
-
 import 'package:analysis_server/src/constants.dart';
 import 'package:analyzer/src/generated/element.dart' as engine;
 import 'package:analyzer/src/generated/utilities_dart.dart' as engine;
@@ -81,7 +79,7 @@ class Element {
         isStatic: _isStatic(element));
   }
 
-  factory Element.fromJson(HashMap<String, Object> map) {
+  factory Element.fromJson(Map<String, Object> map) {
     ElementKind kind = ElementKind.valueOf(map[KIND]);
     int flags = map[FLAGS];
     return new Element(kind, map[NAME], map[OFFSET], map[LENGTH], _hasFlag(
@@ -102,8 +100,8 @@ class Element {
     return flags;
   }
 
-  HashMap<String, Object> toJson() {
-    HashMap<String, Object> json = {
+  Map<String, Object> toJson() {
+    Map<String, Object> json = {
       KIND: kind.name,
       NAME: name,
       OFFSET: offset,