[kernel] Add offset to SwitchContinueStatement; add debugging test

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

Index: pkg/front_end/lib/src/fasta/kernel/body_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
index bf20af0fbd5db011776be0ddda3d9b217adc9b07..5442e3c041de384b0cd6850e96678d8d352f17a0 100644
--- a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
@@ -2994,7 +2994,8 @@ class BodyBuilder extends ScopeListener<JumpTarget> implements BuilderHelper {
       if (target.isGotoTarget &&
           target.functionNestingLevel == functionNestingLevel) {
         ContinueSwitchStatement statement =
-            new KernelContinueSwitchStatement(null);
+            new KernelContinueSwitchStatement(null)
+              ..fileOffset = continueKeyword.charOffset;
         target.addGoto(statement);
         push(statement);
         return;