Implement the new '?.' operator in analyzer.

pkg/analyzer/test/generated/parser_test.dart

Index: pkg/analyzer/test/generated/parser_test.dart
diff --git a/pkg/analyzer/test/generated/parser_test.dart b/pkg/analyzer/test/generated/parser_test.dart
index ea1fa59687e67f4e00d47accf6d4aebfdb73ac33..2b716bf29e7e75408f8efe6b77d2fbc979fad812 100644
--- a/pkg/analyzer/test/generated/parser_test.dart
+++ b/pkg/analyzer/test/generated/parser_test.dart
@@ -1302,6 +1302,18 @@ class Foo {
         [ParserErrorCode.INVALID_OPERATOR]);
   }
 
+  void test_invalidOperatorAfterSuper_assignableExpression() {
+    _enableNullAwareOperators = true;
+    parse3('parseAssignableExpression', <Object>[false], 'super?.v',
+        [ParserErrorCode.INVALID_OPERATOR_FOR_SUPER]);
+  }
+
+  void test_invalidOperatorAfterSuper_primaryExpression() {
+    _enableNullAwareOperators = true;
+    parse4('parsePrimaryExpression', 'super?.v',
+        [ParserErrorCode.INVALID_OPERATOR_FOR_SUPER]);
+  }
+
   void test_invalidOperatorForSuper() {
     parse4("parseUnaryExpression", "++super",
         [ParserErrorCode.INVALID_OPERATOR_FOR_SUPER]);