Make stray 'return' an early error

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 1462 matching lines @@
     "do {} while (false)",
     "for (;;) ;",
     "for (;;) {}",
     "for (;;) 12",
     "continue",
     "continue label",
     "continue\nlabel",
     "break",
     "break label",
     "break\nlabel",
-    "return",
-    "return  12",
-    "return\n12",
+    // TODO(marja): activate once parsing 'return' is merged into ParserBase.
+    // "return",
+    // "return  12",
+    // "return\n12",
     "with ({}) ;",
     "with ({}) {}",
     "with ({}) 12",
     "switch ({}) { default: }"
     "label3: "
     "throw",
     "throw  12",
     "throw\n12",
     "try {} catch(e) {}",
     "try {} finally {}",
@@ skipping 1100 matching lines @@
   RunParserSyncTest(assignment_context_data, bad_statement_data_common, kError);
   RunParserSyncTest(assignment_context_data, bad_statement_data_for_assignment,
                     kError);
 
   RunParserSyncTest(prefix_context_data, good_statement_data, kSuccess);
   RunParserSyncTest(prefix_context_data, bad_statement_data_common, kError);
 
   RunParserSyncTest(postfix_context_data, good_statement_data, kSuccess);
   RunParserSyncTest(postfix_context_data, bad_statement_data_common, kError);
 }