Use ExpressionClassifier to identify valid arrow function formals

test/cctest/test-parsing.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3545 matching lines @@
     "[] => {}",
     "([]) => {}",
     "(a, []) => {}",
     "([], a) => {}",
     "(a = b) => {}",
     "(a = b, c) => {}",
     "(a, b = c) => {}",
     "(foo ? bar : baz) => {}",
     "(a, foo ? bar : baz) => {}",
     "(foo ? bar : baz, a) => {}",
+    "(a.b, c) => {}",
+    "(c, a.b) => {}",
+    "(a['b'], c) => {}",
+    "(c, a['b']) => {}",
     NULL
   };
 
   // The test is quite slow, so run it with a reduced set of flags.
   static const ParserFlag flags[] = {kAllowLazy};
   static const ParserFlag always_flags[] = { kAllowHarmonyArrowFunctions };
   RunParserSyncTest(context_data, statement_data, kError, flags,
                     arraysize(flags), always_flags, arraysize(always_flags));
 }
 
@@ skipping 2891 matching lines @@
     const char* data[] = {
       "yield",
       "[yield]",
       "{ x : yield }",
       NULL};
     // clang-format on
     RunParserSyncTest(context_data, data, kError, NULL, 0, always_flags,
                       arraysize(always_flags));
   }
 }