Extract hardcoded error strings into a single place and replace them with enum.

src/ia32/debug-ia32.cc

 // Copyright 2012 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 110 matching lines @@
     ASSERT((object_regs & non_object_regs) == 0);
     for (int i = 0; i < kNumJSCallerSaved; i++) {
       int r = JSCallerSavedCode(i);
       Register reg = { r };
       if ((object_regs & (1 << r)) != 0) {
         __ push(reg);
       }
       if ((non_object_regs & (1 << r)) != 0) {
         if (FLAG_debug_code) {
           __ test(reg, Immediate(0xc0000000));
-          __ Assert(zero, "Unable to encode value as smi");
+          __ Assert(zero, kUnableToEncodeValueAsSmi);
         }
         __ SmiTag(reg);
         __ push(reg);
       }
     }
 
 #ifdef DEBUG
     __ RecordComment("// Calling from debug break to runtime - come in - over");
 #endif
     __ Set(eax, Immediate(0));  // No arguments.
@@ skipping 221 matching lines @@
 
 const bool Debug::kFrameDropperSupported = true;
 
 #undef __
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32