Change HashMap declarations back to Map.

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

Index: pkg/analysis_server/lib/src/computer/computer_highlights.dart
diff --git a/pkg/analysis_server/lib/src/computer/computer_highlights.dart b/pkg/analysis_server/lib/src/computer/computer_highlights.dart
index 26772f2cb1fcd980b71c9e47e189b20ff5f97f85..483ce20a84ec16a1b23477fc351f61a8007f7986 100644
--- a/pkg/analysis_server/lib/src/computer/computer_highlights.dart
+++ b/pkg/analysis_server/lib/src/computer/computer_highlights.dart
@@ -18,14 +18,14 @@ import 'package:analyzer/src/generated/scanner.dart';
 class DartUnitHighlightsComputer {
   final CompilationUnit _unit;
 
-  final List<HashMap<String, Object>> _regions = <HashMap<String, Object>>[];
+  final List<Map<String, Object>> _regions = <HashMap<String, Object>>[];
 
   DartUnitHighlightsComputer(this._unit);
 
   /**
    * Returns the computed highlight regions, not `null`.
    */
-  List<HashMap<String, Object>> compute() {
+  List<Map<String, Object>> compute() {
     _unit.accept(new _DartUnitHighlightsComputerVisitor(this));
     return _regions;
   }