Fix NotifyStubFailureSaveDoubles generation for ia32.

src/arguments.cc

 // 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 102 matching lines @@
 
 #undef WRITE_CALL_0
 #undef WRITE_CALL_1
 #undef WRITE_CALL_2
 #undef WRITE_CALL_2_VOID
 
 
 double ClobberDoubleRegisters(double x1, double x2, double x3, double x4) {
   // TODO(ulan): This clobbers only subset of registers depending on compiler,
   // Rewrite this in assembly to really clobber all registers.
+  // GCC for ia32 uses the FPU and does not touch XMM registers.
   return x1 * 1.01 + x2 * 2.02 + x3 * 3.03 + x4 * 4.04;
 }
 
 
 } }  // namespace v8::internal