Port and integrate the irregexp engine from V8

tests/language/regex/no-extensions_test.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'util.dart';
+import 'package:expect/expect.dart';
+
+void main() {
+  description(
+  'Tests that regular expressions do not have extensions that diverge from the JavaScript specification. '
+  + 'Because WebKit originally used a copy of PCRE, various non-JavaScript regular expression features were historically present. '
+  + 'Also tests various related edge cases.'
+  );
+
+  shouldBeNull(new RegExp(r"\\x{41}").firstMatch("yA1"));
+  assertEquals(new RegExp(r"[\x{41}]").firstMatch("yA1").group(0), "1");
+  assertEquals(new RegExp(r"\x1g").firstMatch("x1g").group(0), "x1g");
+  assertEquals(new RegExp(r"[\x1g]").firstMatch("x").group(0), "x");
+  assertEquals(new RegExp(r"[\x1g]").firstMatch("1").group(0), "1");
+  assertEquals(new RegExp(r"\2147483648").firstMatch(new String.fromCharCode(140) + "7483648").group(0), new String.fromCharCode(140) + "7483648");
+  assertEquals(new RegExp(r"\4294967296").firstMatch("\"94967296").group(0), "\"94967296");
+  assertEquals(new RegExp(r"\8589934592").firstMatch("\8589934592").group(0), "\8589934592");
+  assertEquals("\nAbc\n".replaceAllMapped(new RegExp(r"(\n)[^\n]+$"), (m) => m.group(1)), "\nAbc\n");
+  shouldBeNull(new RegExp(r"x$").firstMatch("x\n"));
+  assertThrows(() => new RegExp(r"x++"));
+  shouldBeNull(new RegExp(r"[]]").firstMatch("]"));
+
+  assertEquals(new RegExp(r"\060").firstMatch("y01").group(0), "0");
+  assertEquals(new RegExp(r"[\060]").firstMatch("y01").group(0), "0");
+  assertEquals(new RegExp(r"\606").firstMatch("y06").group(0), "06");
+  assertEquals(new RegExp(r"[\606]").firstMatch("y06").group(0), "0");
+  assertEquals(new RegExp(r"[\606]").firstMatch("y6").group(0), "6");
+  assertEquals(new RegExp(r"\101").firstMatch("yA1").group(0), "A");
+  assertEquals(new RegExp(r"[\101]").firstMatch("yA1").group(0), "A");
+  assertEquals(new RegExp(r"\1011").firstMatch("yA1").group(0), "A1");
+  assertEquals(new RegExp(r"[\1011]").firstMatch("yA1").group(0), "A");
+  assertEquals(new RegExp(r"[\1011]").firstMatch("y1").group(0), "1");
+  assertEquals(new RegExp(r"\10q").firstMatch("y" + new String.fromCharCode(8) + "q").group(0), new String.fromCharCode(8) + "q");
+  assertEquals(new RegExp(r"[\10q]").firstMatch("y" + new String.fromCharCode(8) + "q").group(0), new String.fromCharCode(8));
+  assertEquals(new RegExp(r"\1q").firstMatch("y" + new String.fromCharCode(1) + "q").group(0), new String.fromCharCode(1) + "q");
+  assertEquals(new RegExp(r"[\1q]").firstMatch("y" + new String.fromCharCode(1) + "q").group(0), new String.fromCharCode(1));
+  assertEquals(new RegExp(r"[\1q]").firstMatch("yq").group(0), "q");
+  assertEquals(new RegExp(r"\8q").firstMatch("\8q").group(0), "\8q");
+  assertEquals(new RegExp(r"[\8q]").firstMatch("y8q").group(0), "8");
+  assertEquals(new RegExp(r"[\8q]").firstMatch("yq").group(0), "q");
+  shouldBe(new RegExp(r"(x)\1q").firstMatch("xxq"), ["xxq", "x"]);
+  shouldBe(new RegExp(r"(x)[\1q]").firstMatch("xxq"), ["xq", "x"]);
+  shouldBe(new RegExp(r"(x)[\1q]").firstMatch("xx" + new String.fromCharCode(1)), ["x" + new String.fromCharCode(1), "x"]);
+}