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 ed9348d8638c6b00c6d3f64b8b3f603083915b78..e664c03107b721c0b9e5ca369c5539244791128c 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -3766,6 +3766,11 @@ 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
@@ -3961,6 +3966,7 @@ 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;