Add FallThroughError patch

pkg/dev_compiler/tool/input_sdk/patch/core_patch.dart

Index: pkg/dev_compiler/tool/input_sdk/patch/core_patch.dart
diff --git a/pkg/dev_compiler/tool/input_sdk/patch/core_patch.dart b/pkg/dev_compiler/tool/input_sdk/patch/core_patch.dart
index 6f979795c956d1a8c94f3854e5ff7bdbe1b376a1..83937394714a1d5324d1abc8c22b7663fd39a5fc 100644
--- a/pkg/dev_compiler/tool/input_sdk/patch/core_patch.dart
+++ b/pkg/dev_compiler/tool/input_sdk/patch/core_patch.dart
@@ -165,6 +165,9 @@ class Error {
 @patch
 class FallThroughError {
   @patch
+  FallThroughError._create(String url, int line);
+
+  @patch
   String toString() => super.toString();
 }