Cleanup: Make CheckClassId instruction more general so it

runtime/vm/flow_graph_compiler_arm64.cc

Index: runtime/vm/flow_graph_compiler_arm64.cc
diff --git a/runtime/vm/flow_graph_compiler_arm64.cc b/runtime/vm/flow_graph_compiler_arm64.cc
index 00d61566d17346788bf950eb8e5b891712558666..8f258f73f0d1dbe61444e0dd493e0bbfaacebbaa 100644
--- a/runtime/vm/flow_graph_compiler_arm64.cc
+++ b/runtime/vm/flow_graph_compiler_arm64.cc
@@ -1487,13 +1487,13 @@ int FlowGraphCompiler::EmitTestAndCallCheckCid(Label* next_label,
                                                int bias) {
   intptr_t cid_start = range.cid_start;
   intptr_t cid_end = range.cid_end;
-  if (cid_start == cid_end) {
+  if (range.IsSingleCid()) {
     __ CompareImmediate(R2, cid_start - bias);
     __ b(next_label, NE);
   } else {
     __ AddImmediate(R2, bias - cid_start);
     bias = cid_start;
-    __ CompareImmediate(R2, cid_end - cid_start);
+    __ CompareImmediate(R2, range.Extent());
     __ b(next_label, HI);  // Unsigned higher.
   }
   return bias;