Improve token position for the entry CheckStackoverflowInstr

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
diff --git a/runtime/vm/intermediate_language.h b/runtime/vm/intermediate_language.h
index 76840bb8dc56cb9c7a22b4af1ef4398861681452..f998af80965e321773a784763c69c89998390219 100644
--- a/runtime/vm/intermediate_language.h
+++ b/runtime/vm/intermediate_language.h
@@ -2541,7 +2541,8 @@ class ConstraintInstr : public TemplateDefinition<1, NoThrow> {
 
 class ConstantInstr : public TemplateDefinition<0, NoThrow, Pure> {
  public:
-  explicit ConstantInstr(const Object& value);
+  ConstantInstr(const Object& value,
+                intptr_t token_pos = Scanner::kNoSourcePos);
 
   DECLARE_INSTRUCTION(Constant)
   virtual CompileType ComputeType() const;
@@ -2560,6 +2561,7 @@ class ConstantInstr : public TemplateDefinition<0, NoThrow, Pure> {
 
  private:
   const Object& value_;
+  const intptr_t token_pos_;
 
   DISALLOW_COPY_AND_ASSIGN(ConstantInstr);
 };