Harden a few builtins

src/messages.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // -------------------------------------------------------------------
 
 var kMessages = {
   // Error
   cyclic_proto:                  ["Cyclic __proto__ value"],
   code_gen_from_strings:         ["%0"],
@@ skipping 144 matching lines @@
   generator_poison_pill:         ["'caller' and 'arguments' properties may not be accessed on generator functions."],
   unprotected_let:               ["Illegal let declaration in unprotected statement context."],
   unprotected_const:             ["Illegal const declaration in unprotected statement context."],
   cant_prevent_ext_external_array_elements: ["Cannot prevent extension of an object with external array elements"],
   redef_external_array_element:  ["Cannot redefine a property of an object with external array elements"],
   harmony_const_assign:          ["Assignment to constant variable."],
   symbol_to_string:              ["Cannot convert a Symbol value to a string"],
   symbol_to_primitive:           ["Cannot convert a Symbol wrapper object to a primitive value"],
   invalid_module_path:           ["Module does not export '", "%0", "', or export is not itself a module"],
   module_type_error:             ["Module '", "%0", "' used improperly"],
-  module_export_undefined:       ["Export '", "%0", "' is not defined in module"]
+  module_export_undefined:       ["Export '", "%0", "' is not defined in module"],
+  // Internal error.
+  internal_error:                ["Internal error"]
 };
 
 
 function FormatString(format, args) {
   var result = "";
   var arg_num = 0;
   for (var i = 0; i < format.length; i++) {
     var str = format[i];
     if (str.length == 2 && %_StringCharCodeAt(str, 0) == 0x25) {
       // Two-char string starts with "%".
@@ skipping 166 matching lines @@
 
 function MakeEvalError(type, args) {
   return MakeGenericError($EvalError, type, args);
 }
 
 
 function MakeError(type, args) {
   return MakeGenericError($Error, type, args);
 }
 
+
+function MakeInternalError() {
+  return MakeGenericError($InternalError, "internal_error");
+}
+
 /**
  * Find a line number given a specific source position.
  * @param {number} position The source position.
  * @return {number} 0 if input too small, -1 if input too large,
        else the line number.
  */
 function ScriptLineFromPosition(position) {
   var lower = 0;
   var upper = this.lineCount() - 1;
   var line_ends = this.line_ends;
@@ skipping 815 matching lines @@
     // Store the error function in both the global object
     // and the runtime object. The function is fetched
     // from the runtime object when throwing errors from
     // within the runtime system to avoid strange side
     // effects when overwriting the error functions from
     // user code.
     var name = f.name;
     %SetProperty(global, name, f, DONT_ENUM);
     %SetProperty(builtins, '$' + name, f, DONT_ENUM | DONT_DELETE | READ_ONLY);
     // Configure the error function.
-    if (name == 'Error') {
+    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.
       var ErrorPrototype = function() {};
       %FunctionSetPrototype(ErrorPrototype, $Object.prototype);
       %FunctionSetInstanceClassName(ErrorPrototype, 'Error');
       %FunctionSetPrototype(f, new ErrorPrototype());
-    } else {
+    } else if (name !== 'InternalError') {
       %FunctionSetPrototype(f, new $Error());
     }
     %FunctionSetInstanceClassName(f, 'Error');
     %SetProperty(f.prototype, 'constructor', f, DONT_ENUM);
     %SetProperty(f.prototype, "name", name, DONT_ENUM);
     %SetCode(f, function(m) {
       if (%_IsConstructCall()) {
         // Define all the expected properties directly on the error
         // object. This avoids going through getters and setters defined
         // on prototype objects.
@@ skipping 10 matching lines @@
     %SetNativeFlag(f);
   };
 
   DefineError(function Error() { });
   DefineError(function TypeError() { });
   DefineError(function RangeError() { });
   DefineError(function SyntaxError() { });
   DefineError(function ReferenceError() { });
   DefineError(function EvalError() { });
   DefineError(function URIError() { });
+  DefineError(function InternalError() { });
 }
 
 SetUpError();
 
 $Error.captureStackTrace = captureStackTrace;
 
 %SetProperty($Error.prototype, 'message', '', DONT_ENUM);
 
 // Global list of error objects visited during ErrorToString. This is
 // used to detect cycles in error toString formatting.
@@ skipping 97 matching lines @@
     return result;
   };
 
   %DefineOrRedefineAccessorProperty(
       boilerplate, 'stack', getter, setter, DONT_ENUM);
 
   return boilerplate;
 }
 
 var kStackOverflowBoilerplate = SetUpStackOverflowBoilerplate();