Fix BazelFileUriResolver tests

pkg/analyzer/lib/src/generated/bazel.dart

Index: pkg/analyzer/lib/src/generated/bazel.dart
diff --git a/pkg/analyzer/lib/src/generated/bazel.dart b/pkg/analyzer/lib/src/generated/bazel.dart
index debd30081f18494500f6e764b4e0af294db9c456..fc85e29740b4a071bc86bc2fbd85cdc2cfb77c2d 100644
--- a/pkg/analyzer/lib/src/generated/bazel.dart
+++ b/pkg/analyzer/lib/src/generated/bazel.dart
@@ -57,13 +57,11 @@ class BazelFileUriResolver extends ResourceUriResolver {
   }
 
   String _getPathFromWorkspaceDir(Uri uri) {
-    String uriPath = uri.path;
-    String workspacePath = _workspaceDir.path;
-
-    if (uriPath.startsWith(workspacePath) &&
-        workspacePath.length < uriPath.length) {
-      return uriPath.substring(workspacePath.length + 1);
+    try {
+      return provider.pathContext.relative(provider.pathContext.fromUri(uri),
+          from: _workspaceDir.path);
+    } on Exception {
+      return '';
     }
-    return '';
   }
 }