Make concrete classes for individual call descriptors.

src/arm64/lithium-arm64.h

Index: src/arm64/lithium-arm64.h
diff --git a/src/arm64/lithium-arm64.h b/src/arm64/lithium-arm64.h
index 8e7ef65b5e45bfa1e58b86586aff12eb02473d6c..f8ba5701477f6256c38775a24a395fca0ec84f6e 100644
--- a/src/arm64/lithium-arm64.h
+++ b/src/arm64/lithium-arm64.h
@@ -1523,17 +1523,17 @@ class LInteger32ToDouble FINAL : public LTemplateInstruction<1, 1, 0> {
 
 class LCallWithDescriptor FINAL : public LTemplateResultInstruction<1> {
  public:
-  LCallWithDescriptor(const CallInterfaceDescriptor* descriptor,
+  LCallWithDescriptor(CallInterfaceDescriptor descriptor,
                       const ZoneList<LOperand*>& operands, Zone* zone)
       : descriptor_(descriptor),
-        inputs_(descriptor->GetRegisterParameterCount() + 1, zone) {
-    DCHECK(descriptor->GetRegisterParameterCount() + 1 == operands.length());
+        inputs_(descriptor.GetRegisterParameterCount() + 1, zone) {
+    DCHECK(descriptor.GetRegisterParameterCount() + 1 == operands.length());
     inputs_.AddAll(operands, zone);
   }
 
   LOperand* target() const { return inputs_[0]; }
 
-  const CallInterfaceDescriptor* descriptor() { return descriptor_; }
+  CallInterfaceDescriptor descriptor() { return descriptor_; }
 
  private:
   DECLARE_CONCRETE_INSTRUCTION(CallWithDescriptor, "call-with-descriptor")
@@ -1543,7 +1543,7 @@ class LCallWithDescriptor FINAL : public LTemplateResultInstruction<1> {
 
   int arity() const { return hydrogen()->argument_count() - 1; }
 
-  const CallInterfaceDescriptor* descriptor_;
+  CallInterfaceDescriptor descriptor_;
   ZoneList<LOperand*> inputs_;
 
   // Iterator support.