Don't test directly against Scanner::kNoSourcePos instead use >= 0.

runtime/vm/flow_graph_compiler_x64.cc

Index: runtime/vm/flow_graph_compiler_x64.cc
diff --git a/runtime/vm/flow_graph_compiler_x64.cc b/runtime/vm/flow_graph_compiler_x64.cc
index 6319904d096f6f4b675894a86940af1b48343fe9..4a7c7ab72ae66b1806dd70baaa09ef4773c5a249 100644
--- a/runtime/vm/flow_graph_compiler_x64.cc
+++ b/runtime/vm/flow_graph_compiler_x64.cc
@@ -1410,7 +1410,7 @@ Condition FlowGraphCompiler::EmitEqualityRegConstCompare(
     } else {
       __ CallPatchable(*StubCode::UnoptimizedIdenticalWithNumberCheck_entry());
     }
-    if (token_pos != Scanner::kNoSourcePos) {
+    if (token_pos >= 0) {
       AddCurrentDescriptor(RawPcDescriptors::kRuntimeCall,
                            Thread::kNoDeoptId,
                            token_pos);
@@ -1437,7 +1437,7 @@ Condition FlowGraphCompiler::EmitEqualityRegRegCompare(Register left,
     } else {
       __ CallPatchable(*StubCode::UnoptimizedIdenticalWithNumberCheck_entry());
     }
-    if (token_pos != Scanner::kNoSourcePos) {
+    if (token_pos >= 0) {
       AddCurrentDescriptor(RawPcDescriptors::kRuntimeCall,
                            Thread::kNoDeoptId,
                            token_pos);