Cleanup: Make CheckClassId instruction more general so it

runtime/vm/flow_graph_compiler_ia32.cc

Index: runtime/vm/flow_graph_compiler_ia32.cc
diff --git a/runtime/vm/flow_graph_compiler_ia32.cc b/runtime/vm/flow_graph_compiler_ia32.cc
index 1538e0f7680ba2346a2d328b9b547f4ec21e5a17..9d8eda43599cdf6fa1db9bdaca85cc74feaef7cd 100644
--- a/runtime/vm/flow_graph_compiler_ia32.cc
+++ b/runtime/vm/flow_graph_compiler_ia32.cc
@@ -1457,13 +1457,13 @@ 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()) {
     __ cmpl(EDI, Immediate(cid_start - bias));
     __ j(NOT_EQUAL, next_label);
   } else {
     __ addl(EDI, Immediate(bias - cid_start));
     bias = cid_start;
-    __ cmpl(EDI, Immediate(cid_end - cid_start));
+    __ cmpl(EDI, Immediate(range.Extent()));
     __ j(ABOVE, next_label);  // Unsigned higher.
   }
   return bias;