Fix test for parsing 'await'.

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 cd5912f7f2d31c2f5b59866c0faecb44fd8cb333..05116e4a29e029c7d9b36e54721ee74ca6d14517 100644
--- a/pkg/analyzer/test/generated/parser_fasta_test.dart
+++ b/pkg/analyzer/test/generated/parser_fasta_test.dart
@@ -352,12 +352,6 @@ class ExpressionParserTest_Fasta extends FastaParserTestCase
 
   @override
   @failingTest
-  void test_parseAwaitExpression() {
-    super.test_parseAwaitExpression();
-  }
-
-  @override
-  @failingTest
   void test_parseCascadeSection_ia_typeArgumentComments() {
     super.test_parseCascadeSection_ia_typeArgumentComments();
   }
@@ -747,7 +741,8 @@ class FastaParserTestCase extends Object
 
   @override
   AwaitExpression parseAwaitExpression(String code) {
-    return _parseExpression(code);
+    var function = _parseExpression('() async => $code') as FunctionExpression;
+    return (function.body as ExpressionFunctionBody).expression;
   }
 
   @override