Our JavaScriptFrame::function_slot_object is arch independent.

src/mips64/frames-mips64.h

Index: src/mips64/frames-mips64.h
diff --git a/src/mips64/frames-mips64.h b/src/mips64/frames-mips64.h
index 4434a98b7fb7d0ac42baea8aef76ff09372d2706..9b6d32627526975a696dee2e1174388ce8061e69 100644
--- a/src/mips64/frames-mips64.h
+++ b/src/mips64/frames-mips64.h
@@ -169,12 +169,6 @@ class JavaScriptFrameConstants : public AllStatic {
 };
 
 
-inline Object* JavaScriptFrame::function_slot_object() const {
-  const int offset = JavaScriptFrameConstants::kFunctionOffset;
-  return Memory::Object_at(fp() + offset);
-}
-
-
 } }  // namespace v8::internal
 
 #endif