Make some parser test helper methods non-static.

pkg/analyzer/test/src/dart/analysis/referenced_names_test.dart

Index: pkg/analyzer/test/src/dart/analysis/referenced_names_test.dart
diff --git a/pkg/analyzer/test/src/dart/analysis/referenced_names_test.dart b/pkg/analyzer/test/src/dart/analysis/referenced_names_test.dart
index 97a1bdcaf3f830d53650d12e92f6f4045a97ccbd..f35be9bbf0eb72081cefb5e980ce53a4b49c4127 100644
--- a/pkg/analyzer/test/src/dart/analysis/referenced_names_test.dart
+++ b/pkg/analyzer/test/src/dart/analysis/referenced_names_test.dart
@@ -16,7 +16,7 @@ main() {
 }
 
 @reflectiveTest
-class ReferencedNamesBuilderTest {
+class ReferencedNamesBuilderTest extends ParserTestCase {
   test_class_constructor() {
     Set<String> names = _computeReferencedNames('''
 class U {
@@ -383,7 +383,7 @@ main() {
   }
 
   Set<String> _computeReferencedNames(String code) {
-    CompilationUnit unit = ParserTestCase.parseCompilationUnit2(code);
+    CompilationUnit unit = parseCompilationUnit2(code);
     return computeReferencedNames(unit);
   }
 }