[turbofan] Require proper typing when inferring machine type from big-boy type.

src/compiler/representation-change.cc

Index: src/compiler/representation-change.cc
diff --git a/src/compiler/representation-change.cc b/src/compiler/representation-change.cc
index b630f65245d0d304586ec7e65b09e4b1969e25d8..b4b408d7e032d4554dab7030ce6e7dbed5244011 100644
--- a/src/compiler/representation-change.cc
+++ b/src/compiler/representation-change.cc
@@ -471,8 +471,7 @@ const Operator* RepresentationChanger::Float64OperatorFor(
 
 
 MachineType RepresentationChanger::TypeFromUpperBound(Type* type) {
-  if (type->Is(Type::None()))
-    return kTypeAny;  // TODO(titzer): should be an error
+  CHECK(!type->Is(Type::None()));
   if (type->Is(Type::Signed32())) return kTypeInt32;
   if (type->Is(Type::Unsigned32())) return kTypeUint32;
   if (type->Is(Type::Number())) return kTypeNumber;