ARM64: Preserve x8 and x9 when necessary.

src/arm64/assembler-arm64.h

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 498 matching lines @@
     ASSERT(IsValid());
     list_ = new_list;
   }
 
   // Combine another CPURegList into this one. Registers that already exist in
   // this list are left unchanged. The type and size of the registers in the
   // 'other' list must match those in this list.
   void Combine(const CPURegList& other);
 
   // Remove every register in the other CPURegList from this one. Registers that
-  // do not exist in this list are ignored. The type and size of the registers
-  // in the 'other' list must match those in this list.
+  // do not exist in this list are ignored. The type of the registers in the
+  // 'other' list must match those in this list.
   void Remove(const CPURegList& other);
 
   // Variants of Combine and Remove which take CPURegisters.
   void Combine(const CPURegister& other);
   void Remove(const CPURegister& other1,
               const CPURegister& other2 = NoCPUReg,
               const CPURegister& other3 = NoCPUReg,
               const CPURegister& other4 = NoCPUReg);
 
   // Variants of Combine and Remove which take a single register by its code;
@@ skipping 1707 matching lines @@
 class EnsureSpace BASE_EMBEDDED {
  public:
   explicit EnsureSpace(Assembler* assembler) {
     assembler->CheckBuffer();
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM64_ASSEMBLER_ARM64_H_