Migrate test block 8 to Dart 2.0.

tests/corelib_2/format_exception_test.dart

Index: tests/corelib_2/format_exception_test.dart
diff --git a/tests/corelib_strong/format_exception_test.dart b/tests/corelib_2/format_exception_test.dart
similarity index 84%
rename from tests/corelib_strong/format_exception_test.dart
rename to tests/corelib_2/format_exception_test.dart
index 717b76bc4776780c0ea082a9654fae19f2188ee6..a2e89e6194cca793fa7a7d2abb2a33c5547ea384 100644
--- a/tests/corelib_strong/format_exception_test.dart
+++ b/tests/corelib_2/format_exception_test.dart
@@ -83,4 +83,26 @@ main() {
       "FormatException: message (at line 10, character ${half + 1})\n"
       "...${longline.substring(half - 36, half + 36)}...\n"
       "${' ' * 39}^\n");
+
+  var sourceNL = "\nsource with leading NL";
+  e = new FormatException("message", sourceNL, 2);
+  test(
+      e,
+      "message",
+      sourceNL,
+      2,
+      "FormatException: message (at line 2, character 2)\n"
+      "source with leading NL\n"
+      " ^\n");
+
+  var sourceNL2 = "\n\nsource with leading NL";
+  e = new FormatException("message", sourceNL2, 2);
+  test(
+      e,
+      "message",
+      sourceNL2,
+      2,
+      "FormatException: message (at line 3, character 1)\n"
+      "source with leading NL\n"
+      "^\n");
 }