[turbofan]: Add better encapsulation to LinkageLocation

src/compiler/c-linkage.cc

Index: src/compiler/c-linkage.cc
diff --git a/src/compiler/c-linkage.cc b/src/compiler/c-linkage.cc
index 7ec497601925e5a5e3777451884c707fd7bbbc45..613337c908c5d772fbeea148326b0964df3bb91c 100644
--- a/src/compiler/c-linkage.cc
+++ b/src/compiler/c-linkage.cc
@@ -16,13 +16,13 @@ namespace compiler {
 namespace {
 // Platform-specific configuration for C calling convention.
 LinkageLocation regloc(Register reg) {
-  return LinkageLocation(Register::ToAllocationIndex(reg));
+  return LinkageLocation::ForRegister(Register::ToAllocationIndex(reg));
 }
 
 
 LinkageLocation stackloc(int i) {
   DCHECK_LT(i, 0);
-  return LinkageLocation(i);
+  return LinkageLocation::ForCallerFrameSlot(i);
 }
 
 
@@ -226,7 +226,7 @@ CallDescriptor* Linkage::GetSimplifiedCDescriptor(
 
   // The target for C calls is always an address (i.e. machine pointer).
   MachineType target_type = kMachPtr;
-  LinkageLocation target_loc = LinkageLocation::AnyRegister();
+  LinkageLocation target_loc = LinkageLocation::ForAnyRegister();
   return new (zone) CallDescriptor(  // --
       CallDescriptor::kCallAddress,  // kind
       target_type,                   // target MachineType