[turbofan] Various fixes to allow unboxed doubles as arguments in registers and on the stack.

src/compiler/machine-type.h

Index: src/compiler/machine-type.h
diff --git a/src/compiler/machine-type.h b/src/compiler/machine-type.h
index f152611a14bb7413edb65ec91452ff02260e6349..0cd2a84010b5fd238c7bd140b296462692dc3012 100644
--- a/src/compiler/machine-type.h
+++ b/src/compiler/machine-type.h
@@ -116,6 +116,11 @@ inline int ElementSizeOf(MachineType machine_type) {
   return 1 << shift;
 }
 
+inline bool IsFloatingPoint(MachineType type) {
+  MachineType rep = RepresentationOf(type);
+  return rep == kRepFloat32 || rep == kRepFloat64;
+}
+
 typedef Signature<MachineType> MachineSignature;
 
 }  // namespace compiler