Allow setting breakpoints in function literal field initializers under --dfe.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 719af78f7a40113544473225756f22213f1bfee9..d33ace58f3e4ec1e74f87a1b7dfa78167fd930a3 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -3595,10 +3595,10 @@ class Script : public Object {
   }
   void set_compile_time_constants(const Array& value) const;
 
-  const uint8_t* kernel_data() { return raw_ptr()->kernel_data_; }
+  const uint8_t* kernel_data() const { return raw_ptr()->kernel_data_; }
   void set_kernel_data(const uint8_t* kernel_data) const;
 
-  intptr_t kernel_data_size() { return raw_ptr()->kernel_data_size_; }
+  intptr_t kernel_data_size() const { return raw_ptr()->kernel_data_size_; }
   void set_kernel_data_size(const intptr_t kernel_data_size) const;
 
   intptr_t kernel_script_index() { return raw_ptr()->kernel_script_index_; }