Implement FileState.hashCode/==.

pkg/analyzer/lib/src/dart/analysis/file_state.dart

Index: pkg/analyzer/lib/src/dart/analysis/file_state.dart
diff --git a/pkg/analyzer/lib/src/dart/analysis/file_state.dart b/pkg/analyzer/lib/src/dart/analysis/file_state.dart
index 5d11c9f6215d40a693de381ffd63125283b0dc54..3df2b1ad8c9ac4b65bf94a9f26da7fbfc20bd1b3 100644
--- a/pkg/analyzer/lib/src/dart/analysis/file_state.dart
+++ b/pkg/analyzer/lib/src/dart/analysis/file_state.dart
@@ -119,6 +119,9 @@ class FileState {
    */
   List<FileState> get exportedFiles => _exportedFiles;
 
+  @override
+  int get hashCode => uri.hashCode;
+
   /**
    * The list of files this file imports.
    */
@@ -139,6 +142,11 @@ class FileState {
    */
   UnlinkedUnit get unlinked => _unlinked;
 
+  @override
+  bool operator ==(Object other) {
+    return other is FileState && other.uri == uri;
+  }
+
   /**
    * Return a new parsed unresolved [CompilationUnit].
    */