[test] Split_literals_tests relies on no inlining across the loading units to check constant pools are also deferred.

Change-Id: I3989b7c923ecebf144eae44dc4897177fe4550be
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/326686
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>

runtime/tests/vm/dart/split_literals_deferred.dart

@@ -4,6 +4,7 @@
 
 import "split_literals.dart";
 
+@pragma("vm:never-inline")
 void foo() {
   print("Deferred literal!");
   print(const <String>["Deferred literal in a list!"]);