Remove Error.prototype.toStrings prototype property.

src/messages.js

 // Copyright 2006-2008 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 1041 matching lines @@
   try {
     return %_CallFunction(this, errorToStringDetectCycle);
   } catch(e) {
     // If this error message was encountered already return the empty
     // string for it instead of recursively formatting it.
     if (isCyclicErrorMarker(e)) return '';
     else throw e;
   }
 }
 
-%FunctionSetName(errorToString, 'toString');
-%SetProperty($Error.prototype, 'toString', errorToString, DONT_ENUM);
+
+InstallFunctions($Error.prototype, DONT_ENUM, ['toString', errorToString]);
 
 // Boilerplate for exceptions for stack overflows. Used from
 // Top::StackOverflow().
 const kStackOverflowBoilerplate = MakeRangeError('stack_overflow', []);