Extract ExpressionParserText from SimpleParserTest.

pkg/analyzer/test/generated/parser_fasta_test.dart

Index: pkg/analyzer/test/generated/parser_fasta_test.dart
diff --git a/pkg/analyzer/test/generated/parser_fasta_test.dart b/pkg/analyzer/test/generated/parser_fasta_test.dart
index e7c0c285880d9972730415ce6be8425b3b781db9..c3a6f9ee4796b38512d5fb4cae26806fe7b6908e 100644
--- a/pkg/analyzer/test/generated/parser_fasta_test.dart
+++ b/pkg/analyzer/test/generated/parser_fasta_test.dart
@@ -631,6 +631,14 @@ class FastaParserTestCase extends Object
   }
 
   @override
+  set enableLazyAssignmentOperators(bool value) {
+    // TODO: implement enableLazyAssignmentOperators
+    if (value == true) {
+      throw new UnimplementedError();
+    }
+  }
+
+  @override
   set enableNnbd(bool value) {
     if (value == true) {
       // TODO(paulberry,ahe): non-null-by-default syntax is not supported by