CallInterfaceDescriptorData: clarify comment

Bug: 
Change-Id: If8c9db5ad4114f9ce3ca925d85a776fdb7da8fed
Reviewed-on: https://chromium-review.googlesource.com/513525Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Ali Ijaz Sheikh <ofrobots@google.com>
Cr-Commit-Position: refs/heads/master@{#45610}

src/interface-descriptors.h

@@ -99,13 +99,12 @@ class V8_EXPORT_PRIVATE CallInterfaceDescriptorData {
       PlatformInterfaceDescriptor* platform_descriptor = NULL);
 
   // if machine_types is null, then an array of size
-  // (register_parameter_count + extra_parameter_count) will be created
-  // with MachineType::AnyTagged() for each member.
+  // (parameter_count + extra_parameter_count) will be created with
+  // MachineType::AnyTagged() for each member.
   //
   // if machine_types is not null, then it should be of the size
-  // register_parameter_count. Those members of the parameter array
-  // will be initialized from {machine_types}, and the rest initialized
-  // to MachineType::AnyTagged().
+  // parameter_count. Those members of the parameter array will be initialized
+  // from {machine_types}, and the rest initialized to MachineType::AnyTagged().
   void InitializePlatformIndependent(int parameter_count,
                                      int extra_parameter_count,
                                      const MachineType* machine_types);