Use the macro assembler Set instead of explicit xor for clearing registers.

src/ia32/debug-ia32.cc

 // Copyright 2010 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 107 matching lines @@
         __ Assert(zero, "Unable to encode value as smi");
       }
       __ SmiTag(reg);
       __ push(reg);
     }
   }
 
 #ifdef DEBUG
   __ RecordComment("// Calling from debug break to runtime - come in - over");
 #endif
-  __ Set(eax, Immediate(0));  // no arguments
+  __ Set(eax, Immediate(0));  // No arguments.
   __ mov(ebx, Immediate(ExternalReference::debug_break()));
 
   CEntryStub ceb(1);
   __ CallStub(&ceb);
 
   // Restore the register values containing object pointers from the expression
   // stack.
   for (int i = kNumJSCallerSaved; --i >= 0;) {
     int r = JSCallerSavedCode(i);
     Register reg = { r };
@@ skipping 161 matching lines @@
 
 const bool Debug::kFrameDropperSupported = true;
 
 #undef __
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32