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

runtime/vm/flow_graph_compiler_mips.cc

Index: runtime/vm/flow_graph_compiler_mips.cc
diff --git a/runtime/vm/flow_graph_compiler_mips.cc b/runtime/vm/flow_graph_compiler_mips.cc
index 3c7f8e99c6584817d4e622dc90a8d114561e0001..83919f5aeac6e70bada29f64b934365bd77471f3 100644
--- a/runtime/vm/flow_graph_compiler_mips.cc
+++ b/runtime/vm/flow_graph_compiler_mips.cc
@@ -1420,7 +1420,7 @@ Condition FlowGraphCompiler::EmitEqualityRegConstCompare(
       __ BranchLinkPatchable(
           *StubCode::UnoptimizedIdenticalWithNumberCheck_entry());
     }
-    if (token_pos != Scanner::kNoSourcePos) {
+    if (token_pos >= 0) {
       AddCurrentDescriptor(RawPcDescriptors::kRuntimeCall,
                            Thread::kNoDeoptId,
                            token_pos);
@@ -1454,7 +1454,7 @@ Condition FlowGraphCompiler::EmitEqualityRegRegCompare(Register left,
       __ BranchLinkPatchable(
           *StubCode::UnoptimizedIdenticalWithNumberCheck_entry());
     }
-    if (token_pos != Scanner::kNoSourcePos) {
+    if (token_pos >= 0) {
       AddCurrentDescriptor(RawPcDescriptors::kRuntimeCall,
                            Thread::kNoDeoptId,
                            token_pos);