Reapply "Support for precise stepping in functions compiled before debugging was started (step 2)"

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 5a1a4a38046727dd4bfda5cdee1f4bb8313e5e68..39c1af0bd0fdc236cc92fa9b0156b0eb54283eff 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -3677,6 +3677,11 @@ class Code: public HeapObject {
   inline bool has_debug_break_slots();
   inline void set_has_debug_break_slots(bool value);
 
+  // [compiled_with_optimizing]: For FUNCTION kind, tells if it has
+  // been compiled with IsOptimizing set to true.
+  inline bool is_compiled_optimizable();
+  inline void set_compiled_optimizable(bool value);
+
   // [allow_osr_at_loop_nesting_level]: For FUNCTION kind, tells for
   // how long the function has been marked for OSR and therefore which
   // level of loop nesting we are willing to do on-stack replacement
@@ -3872,6 +3877,7 @@ class Code: public HeapObject {
   class FullCodeFlagsHasDeoptimizationSupportField:
       public BitField<bool, 0, 1> {};  // NOLINT
   class FullCodeFlagsHasDebugBreakSlotsField: public BitField<bool, 1, 1> {};
+  class FullCodeFlagsIsCompiledOptimizable: public BitField<bool, 2, 1> {};
 
   static const int kBinaryOpReturnTypeOffset = kBinaryOpTypeOffset + 1;