Add back references. Since "back references" is two words...

test/cctest/test-regexp.cc

 // Copyright 2006-2008 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 142 matching lines @@
                                " (# 0 - g '\\x04'))");
   CHECK_PARSE_EQ("(x)(x)(x)(x)(x)(x)(x)(x)(x)(x)\\10",
               "(: (^ 'x') (^ 'x') (^ 'x') (^ 'x') (^ 'x') (^ 'x')"
               " (^ 'x') (^ 'x') (^ 'x') (^ 'x') (<- 10))");
   CHECK_PARSE_EQ("(x)(x)(x)(x)(x)(x)(x)(x)(x)(x)\\11",
               "(: (^ 'x') (^ 'x') (^ 'x') (^ 'x') (^ 'x') (^ 'x')"
               " (^ 'x') (^ 'x') (^ 'x') (^ 'x') '\\x09')");
   CHECK_PARSE_EQ("(a)\\1", "(: (^ 'a') (<- 1))");
   CHECK_PARSE_EQ("(a\\1)", "(^ 'a')");
   CHECK_PARSE_EQ("(\\1a)", "(^ 'a')");
-  CHECK_PARSE_EQ("\\1(a)", "(: '\\x01' (^ 'a'))");
+  CHECK_PARSE_EQ("\\1(a)", "(^ 'a')");
   CHECK_PARSE_EQ("(?!(a))\\1", "(-> - (^ 'a'))");
-  CHECK_PARSE_EQ("(?!\\1(a\\1)\\1)\\1", "(-> - (: '\\x01' (^ 'a') (<- 1)))");
+  CHECK_PARSE_EQ("(?!\\1(a\\1)\\1)\\1", "(-> - (: (^ 'a') (<- 1)))");
   CHECK_PARSE_EQ("[\\0]", "[\\x00]");
   CHECK_PARSE_EQ("[\\11]", "[\\x09]");
   CHECK_PARSE_EQ("[\\11a]", "[\\x09 a]");
   CHECK_PARSE_EQ("[\\011]", "[\\x09]");
   CHECK_PARSE_EQ("[\\00011]", "[\\x00 1 1]");
   CHECK_PARSE_EQ("[\\118]", "[\\x09 8]");
   CHECK_PARSE_EQ("[\\111]", "[I]");
   CHECK_PARSE_EQ("[\\1111]", "[I 1]");
   CHECK_PARSE_EQ("\\x34", "'\x34'");
   CHECK_PARSE_EQ("\\x60", "'\x60'");
@@ skipping 13 matching lines @@
   CHECK_ESCAPES("a*?", false);
   CHECK_ESCAPES("a?", false);
   CHECK_ESCAPES("a??", false);
   CHECK_ESCAPES("a{0,1}?", false);
   CHECK_ESCAPES("a{1,1}?", false);
   CHECK_ESCAPES("a{1,2}?", false);
   CHECK_ESCAPES("a+?", false);
   CHECK_ESCAPES("(a)", false);
   CHECK_ESCAPES("(a)\\1", false);
   CHECK_ESCAPES("(\\1a)", false);
-  CHECK_ESCAPES("\\1(a)", true);
+  CHECK_ESCAPES("\\1(a)", false);
   CHECK_ESCAPES("a\\s", false);
   CHECK_ESCAPES("a\\S", false);
   CHECK_ESCAPES("a\\d", false);
   CHECK_ESCAPES("a\\D", false);
   CHECK_ESCAPES("a\\w", false);
   CHECK_ESCAPES("a\\W", false);
   CHECK_ESCAPES("a.", false);
   CHECK_ESCAPES("a\\q", true);
   CHECK_ESCAPES("a[a]", false);
   CHECK_ESCAPES("a[^a]", false);
@@ skipping 597 matching lines @@
 TEST(SimplePropagation) {
   v8::HandleScope scope;
   ZoneScope zone_scope(DELETE_ON_EXIT);
   RegExpNode* node = Compile("(a|^b|c)");
   CHECK(node->info()->determine_start);
 }
 
 
 TEST(Graph) {
   V8::Initialize(NULL);
-  Execute(".*o(?=o)", "", true);
+  Execute("(x)?\\1y", "", true);
 }