Decouple root visitors from object visitors.

src/frames.h

Index: src/frames.h
diff --git a/src/frames.h b/src/frames.h
index 990e4ffcc8385312d972a4837b5a6041dc4afa34..fb786df539d7b31d6a1a53ad8f6482c411d75973 100644
--- a/src/frames.h
+++ b/src/frames.h
@@ -36,6 +36,7 @@ int JSCallerSavedCode(int n);
 // Forward declarations.
 class ExternalCallbackScope;
 class Isolate;
+class RootVisitor;
 class StackFrameIteratorBase;
 class ThreadLocalTop;
 class WasmInstanceObject;
@@ -595,8 +596,8 @@ class StackFrame BASE_EMBEDDED {
                                 SafepointEntry* safepoint_entry,
                                 unsigned* stack_slots);
 
-  virtual void Iterate(ObjectVisitor* v) const = 0;
-  static void IteratePc(ObjectVisitor* v, Address* pc_address,
+  virtual void Iterate(RootVisitor* v) const = 0;
+  static void IteratePc(RootVisitor* v, Address* pc_address,
                         Address* constant_pool_address, Code* holder);
 
   // Sets a callback function for return-address rewriting profilers
@@ -667,7 +668,7 @@ class EntryFrame: public StackFrame {
   Code* unchecked_code() const override;
 
   // Garbage collection support.
-  void Iterate(ObjectVisitor* v) const override;
+  void Iterate(RootVisitor* v) const override;
 
   static EntryFrame* cast(StackFrame* frame) {
     DCHECK(frame->is_entry());
@@ -720,7 +721,7 @@ class ExitFrame: public StackFrame {
   Object*& code_slot() const;
 
   // Garbage collection support.
-  void Iterate(ObjectVisitor* v) const override;
+  void Iterate(RootVisitor* v) const override;
 
   void SetCallerFp(Address caller_fp) override;
 
@@ -999,7 +1000,7 @@ class StandardFrame : public StackFrame {
 
   // Iterate over expression stack including stack handlers, locals,
   // and parts of the fixed part including context and code fields.
-  void IterateExpressions(ObjectVisitor* v) const;
+  void IterateExpressions(RootVisitor* v) const;
 
   // Returns the address of the n'th expression stack element.
   virtual Address GetExpressionAddress(int n) const;
@@ -1013,7 +1014,7 @@ class StandardFrame : public StackFrame {
   static inline bool IsConstructFrame(Address fp);
 
   // Used by OptimizedFrames and StubFrames.
-  void IterateCompiledFrame(ObjectVisitor* v) const;
+  void IterateCompiledFrame(RootVisitor* v) const;
 
  private:
   friend class StackFrame;
@@ -1063,7 +1064,7 @@ class JavaScriptFrame : public StandardFrame {
   int GetArgumentsLength() const;
 
   // Garbage collection support.
-  void Iterate(ObjectVisitor* v) const override;
+  void Iterate(RootVisitor* v) const override;
 
   // Printing support.
   void Print(StringStream* accumulator, PrintMode mode,
@@ -1115,7 +1116,7 @@ class JavaScriptFrame : public StandardFrame {
 
   // Garbage collection support. Iterates over incoming arguments,
   // receiver, and any callee-saved registers.
-  void IterateArguments(ObjectVisitor* v) const;
+  void IterateArguments(RootVisitor* v) const;
 
   virtual void PrintFrameKind(StringStream* accumulator) const {}
 
@@ -1131,7 +1132,7 @@ class StubFrame : public StandardFrame {
   Type type() const override { return STUB; }
 
   // GC support.
-  void Iterate(ObjectVisitor* v) const override;
+  void Iterate(RootVisitor* v) const override;
 
   // Determine the code for the frame.
   Code* unchecked_code() const override;
@@ -1158,7 +1159,7 @@ class OptimizedFrame : public JavaScriptFrame {
   Type type() const override { return OPTIMIZED; }
 
   // GC support.
-  void Iterate(ObjectVisitor* v) const override;
+  void Iterate(RootVisitor* v) const override;
 
   // Return a list with {SharedFunctionInfo} objects of this frame.
   // The functions are ordered bottom-to-top (i.e. functions.last()
@@ -1291,7 +1292,7 @@ class WasmCompiledFrame final : public StandardFrame {
   Type type() const override { return WASM_COMPILED; }
 
   // GC support.
-  void Iterate(ObjectVisitor* v) const override;
+  void Iterate(RootVisitor* v) const override;
 
   // Printing support.
   void Print(StringStream* accumulator, PrintMode mode,
@@ -1333,7 +1334,7 @@ class WasmInterpreterEntryFrame final : public StandardFrame {
   Type type() const override { return WASM_INTERPRETER_ENTRY; }
 
   // GC support.
-  void Iterate(ObjectVisitor* v) const override;
+  void Iterate(RootVisitor* v) const override;
 
   // Printing support.
   void Print(StringStream* accumulator, PrintMode mode,
@@ -1393,7 +1394,7 @@ class InternalFrame: public StandardFrame {
   Type type() const override { return INTERNAL; }
 
   // Garbage collection support.
-  void Iterate(ObjectVisitor* v) const override;
+  void Iterate(RootVisitor* v) const override;
 
   // Determine the code for the frame.
   Code* unchecked_code() const override;
@@ -1421,7 +1422,7 @@ class StubFailureTrampolineFrame: public StandardFrame {
   // This method could be called during marking phase of GC.
   Code* unchecked_code() const override;
 
-  void Iterate(ObjectVisitor* v) const override;
+  void Iterate(RootVisitor* v) const override;
 
   // Architecture-specific register description.
   static Register fp_register();