[turbofan] Rename floating point register / slot methods.

src/compiler/gap-resolver.cc

Index: src/compiler/gap-resolver.cc
diff --git a/src/compiler/gap-resolver.cc b/src/compiler/gap-resolver.cc
index 35e91fa40404b98da6d3deb932441358c8ec4578..9403d35f06160c6e2d50a75838dbbda811cfe7de 100644
--- a/src/compiler/gap-resolver.cc
+++ b/src/compiler/gap-resolver.cc
@@ -94,7 +94,7 @@ void GapResolver::PerformMove(ParallelMove* moves, MoveOperands* move) const {
 
   DCHECK((*blocker)->IsPending());
   // Ensure source is a register or both are stack slots, to limit swap cases.
-  if (source.IsStackSlot() || source.IsDoubleStackSlot()) {
+  if (source.IsStackSlot() || source.IsFPStackSlot()) {
     std::swap(source, destination);
   }
   assembler_->AssembleSwap(&source, &destination);