Migrated test block 19 to Dart 2.0.

tests/corelib_2/regexp/global_test.dart

 // Copyright (c) 2014, the Dart project authors. All rights reserved.
 // 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
@@ skipping 42 matching lines @@
     if (m.group(2) != null) return "+";
     if (m.group(3) != null) return "=";
   });
   assertEquals("= -. +, or + -. There is - =.", str);
 
   // Test multiple alternate captures.
   str = "FOUR LEGS GOOD, TWO LEGS BAD!";
   str = str.replaceAllMapped(new RegExp(r"(FOUR|TWO) LEGS (GOOD|BAD)"), (m) {
     if (m.group(1) == "FOUR") assertTrue(m.group(2) == "GOOD");
     if (m.group(1) == "TWO") assertTrue(m.group(2) == "BAD");
-    return m.group(0).length - 10;
+    return (m.group(0).length - 10).toString();
   });
   assertEquals("4, 2!", str);
 
   // The same tests with UC16.
 
   //Test that an optional capture is cleared between two matches.
   str = "AB\u1234 \u1234";
   str = str.replaceAll(new RegExp(r"(\w)?\u1234"), "c");
   assertEquals("Ac c", str);
 
@@ skipping 15 matching lines @@
     if (m.group(2) != null) return "+";
     if (m.group(3) != null) return "=";
   });
   assertEquals("= -. +, or + -. There is - =.", str);
 
   // Test multiple alternate captures.
   str = "FOUR \u817f GOOD, TWO \u817f BAD!";
   str = str.replaceAllMapped(new RegExp(r"(FOUR|TWO) \u817f (GOOD|BAD)"), (m) {
     if (m.group(1) == "FOUR") assertTrue(m.group(2) == "GOOD");
     if (m.group(1) == "TWO") assertTrue(m.group(2) == "BAD");
-    return m.group(0).length - 7;
+    return (m.group(0).length - 7).toString();
   });
   assertEquals("4, 2!", str);
 
   // Test capture that is a real substring.
   str = "Beasts of England, beasts of Ireland";
   str = str.replaceAll(new RegExp(r"(.*)"), '~');
   assertEquals("~~", str);
 
   // Test zero-length matches that have non-zero-length sub-captures that do not
   // start at the match start position.
@@ skipping 65 matching lines @@
   var crosscheck = "\x80";
   for (var i = 0; i < 12; i++) crosscheck += crosscheck;
   new RegExp(crosscheck);
 
   var subject = "ascii~only~string~here~";
   var replacement = "\x80";
   var result = subject.replaceAll(new RegExp(r"~"), replacement);
   for (var i = 0; i < 5; i++) result += result;
   new RegExp(result);
 }