Handle switch continue

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

Index: pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
diff --git a/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart b/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
index 243e5c48a9a1a78055eb13df0687411068004e52..78980315d9c85fb30af7d0727705a2003e1bfd69 100644
--- a/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
+++ b/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
@@ -621,10 +621,11 @@ class KernelSwitchCaseJumpHandler extends SwitchCaseJumpHandler {
     for (ir.SwitchCase switchCase in switchStatement.cases) {
       JumpTarget continueTarget =
           localsMap.getJumpTargetForSwitchCase(switchCase);
-      assert(continueTarget is KernelJumpTarget);
-      targetIndexMap[continueTarget] = switchIndex;
-      assert(builder.jumpTargets[continueTarget] == null);
-      builder.jumpTargets[continueTarget] = this;
+      if (continueTarget != null) {
+        targetIndexMap[continueTarget] = switchIndex;
+        assert(builder.jumpTargets[continueTarget] == null);
+        builder.jumpTargets[continueTarget] = this;
+      }
       switchIndex++;
     }
   }