Introduce the SetFp function in StackHandler

src/x64/frames-x64.h

Index: src/x64/frames-x64.h
diff --git a/src/x64/frames-x64.h b/src/x64/frames-x64.h
index a24ab5310723c0e108adbd27f4aafb5a081aa317..2af5a81bb5f3df194bf8ca1e692591ed680feb2a 100644
--- a/src/x64/frames-x64.h
+++ b/src/x64/frames-x64.h
@@ -126,6 +126,12 @@ inline Object* JavaScriptFrame::function_slot_object() const {
   return Memory::Object_at(fp() + offset);
 }
 
+
+inline void StackHandler::SetFp(Address slot, Address fp) {
+  Memory::Address_at(slot) = fp;
+}
+
+
 } }  // namespace v8::internal
 
 #endif  // V8_X64_FRAMES_X64_H_