[debugger] infrastructure for side-effect-free debug-evaluate.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 3eda230a939a1b5163516c1bdec461972e117a34..47ca57218476fc9c323c064dd0135e6cde822aa4 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -7363,6 +7363,9 @@ class SharedFunctionInfo: public HeapObject {
   // The function's name if it is non-empty, otherwise the inferred name.
   String* DebugName();
 
+  // The function cannot cause any side effects.
+  bool IsReadOnly();
+
   // Used for flags such as --hydrogen-filter.
   bool PassesFilter(const char* raw_filter);
 
@@ -7472,6 +7475,12 @@ class SharedFunctionInfo: public HeapObject {
   // Indicates that asm->wasm conversion failed and should not be re-attempted.
   DECL_BOOLEAN_ACCESSORS(is_asm_wasm_broken)
 
+  // Indicates that the function cannot cause side-effects.
+  DECL_BOOLEAN_ACCESSORS(is_readonly)
+
+  // Indicates that |is_readonly| has been computed and set.
+  DECL_BOOLEAN_ACCESSORS(is_readonly_computed)
+
   inline FunctionKind kind() const;
   inline void set_kind(FunctionKind kind);
 
@@ -7758,6 +7767,8 @@ class SharedFunctionInfo: public HeapObject {
     // byte 3
     kDeserialized = kFunctionKind + 10,
     kIsAsmWasmBroken,
+    kIsReadOnly,
+    kIsReadOnlyComputed,
     kCompilerHintsCount,  // Pseudo entry
   };
   // kFunctionKind has to be byte-aligned