[turbofan]: Elide extra move when accessing stack or frame register

src/mips/frames-mips.cc

Index: src/mips/frames-mips.cc
diff --git a/src/mips/frames-mips.cc b/src/mips/frames-mips.cc
index 3e6293e2e5a8a33ce62c7393c616f7f314826746..7359091923e21aa89ef116a26a8fb7656dc5a55c 100644
--- a/src/mips/frames-mips.cc
+++ b/src/mips/frames-mips.cc
@@ -15,7 +15,8 @@ namespace v8 {
 namespace internal {
 
 
-Register JavaScriptFrame::fp_register() { return v8::internal::fp; }
+Register StandardFrame::sp_register() { return v8::internal::sp; }
+Register StandardFrame::fp_register() { return v8::internal::fp; }
 Register JavaScriptFrame::context_register() { return cp; }
 Register JavaScriptFrame::constant_pool_pointer_register() {
   UNREACHABLE();