Fix ARM build for gcc-4.6

src/arm/code-stubs-arm.cc

 // Copyright 2011 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 2406 matching lines @@
 void BinaryOpStub::GenerateSmiCode(
     MacroAssembler* masm,
     Label* use_runtime,
     Label* gc_required,
     SmiCodeGenerateHeapNumberResults allow_heapnumber_results) {
   Label not_smis;
 
   Register left = r1;
   Register right = r0;
   Register scratch1 = r7;
-  Register scratch2 = r9;
 
   // Perform combined smi check on both operands.
   __ orr(scratch1, left, Operand(right));
   STATIC_ASSERT(kSmiTag == 0);
   __ JumpIfNotSmi(scratch1, &not_smis);
 
   // If the smi-smi operation results in a smi return is generated.
   GenerateSmiSmiOperation(masm);
 
   // If heap number results are possible generate the result in an allocated
@@ skipping 665 matching lines @@
     __ bind(&invalid_cache);
     ExternalReference runtime_function =
         ExternalReference(RuntimeFunction(), masm->isolate());
     __ TailCallExternalReference(runtime_function, 1, 1);
   } else {
     if (!CpuFeatures::IsSupported(VFP3)) UNREACHABLE();
     CpuFeatures::Scope scope(VFP3);
 
     Label no_update;
     Label skip_cache;
-    const Register heap_number_map = r5;
 
     // Call C function to calculate the result and update the cache.
     // Register r0 holds precalculated cache entry address; preserve
     // it on the stack and pop it into register cache_entry after the
     // call.
     __ push(cache_entry);
     GenerateCallCFunction(masm, scratch0);
     __ GetCFunctionDoubleResult(d2);
 
     // Try to update the cache. If we cannot allocate a
@@ skipping 3443 matching lines @@
   __ mov(result, Operand(0));
   __ Ret();
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM