Make functions on the built-in object non-writable.

src/messages.js

 // 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 10 matching lines @@
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 
 // -------------------------------------------------------------------
 //
-// Matches Script::Type from objects.h
-var TYPE_NATIVE = 0;
-var TYPE_EXTENSION = 1;
-var TYPE_NORMAL = 2;
-
-// Matches Script::CompilationType from objects.h
-var COMPILATION_TYPE_HOST = 0;
-var COMPILATION_TYPE_EVAL = 1;
-var COMPILATION_TYPE_JSON = 2;
-
-// Matches Messages::kNoLineNumberInfo from v8.h
-var kNoLineNumberInfo = 0;
-
 // If this object gets passed to an error constructor the error will
 // get an accessor for .message that constructs a descriptive error
 // message on access.
 const kAddMessageAccessorsMarker = { };
 
 // This will be lazily initialized when first needed (and forcibly
 // overwritten even though it's const).
 const kMessages = 0;
 
 function FormatString(format, message) {
@@ skipping 980 matching lines @@
 
   function DefineError(f) {
     // Store the error function in both the global object
     // and the runtime object. The function is fetched
     // from the runtime object when throwing errors from
     // within the runtime system to avoid strange side
     // effects when overwriting the error functions from
     // user code.
     var name = f.name;
     %SetProperty(global, name, f, DONT_ENUM);
-    builtins['$' + name] = f;
+    %SetProperty(builtins, '$' + name, f, DONT_ENUM | DONT_DELETE | READ_ONLY);
     // Configure the error function.
     if (name == 'Error') {
       // The prototype of the Error object must itself be an error.
       // However, it can't be an instance of the Error object because
       // it hasn't been properly configured yet.  Instead we create a
       // special not-a-true-error-but-close-enough object.
       function ErrorPrototype() {}
       %FunctionSetPrototype(ErrorPrototype, $Object.prototype);
       %FunctionSetInstanceClassName(ErrorPrototype, 'Error');
       %FunctionSetPrototype(f, new ErrorPrototype());
@@ skipping 90 matching lines @@
     throw e;
   }
 }
 
 
 InstallFunctions($Error.prototype, DONT_ENUM, ['toString', errorToString]);
 
 // Boilerplate for exceptions for stack overflows. Used from
 // Isolate::StackOverflow().
 const kStackOverflowBoilerplate = MakeRangeError('stack_overflow', []);