Remove the is_used_ field from BindInstr.

runtime/vm/intermediate_language_test.cc

Index: runtime/vm/intermediate_language_test.cc
diff --git a/runtime/vm/intermediate_language_test.cc b/runtime/vm/intermediate_language_test.cc
index 1b571acb71dc16eb44f7bc6e8d861dcdfa6c5bb3..28d2b5c55e88aa31d6ad75a43928a62e1e1152d5 100644
--- a/runtime/vm/intermediate_language_test.cc
+++ b/runtime/vm/intermediate_language_test.cc
@@ -13,7 +13,7 @@ TEST_CASE(InstructionTests) {
   EXPECT(target_instr->IsBlockEntry());
   EXPECT(!target_instr->IsBind());
   BindInstr* bind_instr =
-      new BindInstr(BindInstr::kUnused, new CurrentContextComp());
+      new BindInstr(Definition::kEffect, new CurrentContextComp());
   EXPECT(bind_instr->IsBind());
   EXPECT(!bind_instr->IsBlockEntry());
 }