Don't call deprecated "isPotentiallyMutated..." API from analysis server.

pkg/analysis_server/lib/src/status/validator.dart

Index: pkg/analysis_server/lib/src/status/validator.dart
diff --git a/pkg/analysis_server/lib/src/status/validator.dart b/pkg/analysis_server/lib/src/status/validator.dart
index 07f34b3c9e74b5f038d813499eb698eda157a0a9..5651b8e3ccbb2cf1981bd6175d26fb26d4ca0417 100644
--- a/pkg/analysis_server/lib/src/status/validator.dart
+++ b/pkg/analysis_server/lib/src/status/validator.dart
@@ -708,24 +708,6 @@ class ElementComparator {
           (VariableElement element) =>
               element.isFinal ? 'a final $kind' : 'a non-final $kind');
     }
-    if (expected.isPotentiallyMutatedInClosure !=
-        actual.isPotentiallyMutatedInClosure) {
-      _writeMismatch(
-          expected,
-          actual,
-          (VariableElement element) => element.isPotentiallyMutatedInClosure
-              ? 'a $kind that is potentially mutated in a closure'
-              : 'a $kind that is not mutated in a closure');
-    }
-    if (expected.isPotentiallyMutatedInScope !=
-        actual.isPotentiallyMutatedInScope) {
-      _writeMismatch(
-          expected,
-          actual,
-          (VariableElement element) => element.isPotentiallyMutatedInScope
-              ? 'a $kind that is potentially mutated in its scope'
-              : 'a $kind that is not mutated in its scope');
-    }
     if (expected.isStatic != actual.isStatic) {
       _writeMismatch(
           expected,