Scanner: disallow unicode escapes in regexp flags.

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 4284 matching lines @@
 
 
 TEST(InvalidUnicodeEscapes) {
   const char* context_data[][2] = {{"", ""},
                                    {"'use strict';", ""},
                                    {NULL, NULL}};
   const char* data[] = {
     "var foob\\u123r = 0;",
     "var \\u123roo = 0;",
     "\"foob\\u123rr\"",
-    "/regex/g\\u123r",
+    // No escapes allowed in regexp flags
+    "/regex/\\u0069g",
+    "/regex/\\u006g",
     NULL};
   RunParserSyncTest(context_data, data, kError);
 }