Change the badly named RegExp.pattern to return the original source.

tests/corelib/reg_exp_pattern_test.dart

Index: tests/corelib/reg_exp_pattern_test.dart
diff --git a/tests/language/reg_exp3_test.dart b/tests/corelib/reg_exp_pattern_test.dart
similarity index 50%
copy from tests/language/reg_exp3_test.dart
copy to tests/corelib/reg_exp_pattern_test.dart
index 6c2d68b79087528176eaaefbd7c220f592356d1b..bb7bf10382b8300193539eeda3ea91e86907949f 100644
--- a/tests/language/reg_exp3_test.dart
+++ b/tests/corelib/reg_exp_pattern_test.dart
@@ -5,19 +5,23 @@
 
 import "package:expect/expect.dart";
 
-class RegExp3Test {
-  static testMain() {
-    var i = 2000;
-    try {
-      RegExp exp = new RegExp("[");
-      i = 100;  // Should not reach here.
-    } on FormatException catch (e) {
-      i = 0;
-    }
-    Expect.equals(0, i);
-  }
-}
+// Regression test for http://dartbug.com/17998
 
 main() {
-  RegExp3Test.testMain();
+  for (var s in [
+         r"a",
+         r"a|b",
+         r"(?:)",
+         r"^",
+         r"$",
+         r"^$",
+         r"$^",
+         r"",
+         r"\\",
+         r"/",
+         r"[^]",
+         "\x00",
+       ]) {
+    Expect.equals(s, new RegExp(s).pattern);
+  }
 }