Handle labelled continue statements

pkg/compiler/lib/src/ssa/jump_handler.dart

Index: pkg/compiler/lib/src/ssa/jump_handler.dart
diff --git a/pkg/compiler/lib/src/ssa/jump_handler.dart b/pkg/compiler/lib/src/ssa/jump_handler.dart
index 0050e4abd44c93af318e5acc0be0811c0f622036..91955fb8fff6ca55e48caa989aff1443406e364d 100644
--- a/pkg/compiler/lib/src/ssa/jump_handler.dart
+++ b/pkg/compiler/lib/src/ssa/jump_handler.dart
@@ -99,7 +99,7 @@ class TargetJumpHandler implements JumpHandler {
       continueInstruction = new HContinue.toLabel(label);
       // Switch case continue statements must be handled by the
       // [SwitchCaseJumpHandler].
-      assert(label.target.statement is! ast.SwitchCase);
+      assert(!label.target.isSwitchCase);
     }
     LocalsHandler locals = new LocalsHandler.from(builder.localsHandler);
     builder.close(continueInstruction);