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

src/runtime.h

 // 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 299 matching lines @@
   F(NewFunctionContext, 1, 1) \
   F(PushWithContext, 2, 1) \
   F(PushCatchContext, 3, 1) \
   F(PushBlockContext, 2, 1) \
   F(DeleteContextSlot, 2, 1) \
   F(LoadContextSlot, 2, 2) \
   F(LoadContextSlotNoReferenceError, 2, 2) \
   F(StoreContextSlot, 4, 1) \
   \
   /* Declarations and initialization */ \
-  F(DeclareGlobals, 4, 1) \
+  F(DeclareGlobals, 3, 1) \
   F(DeclareContextSlot, 4, 1) \
   F(InitializeVarGlobal, -1 /* 2 or 3 */, 1) \
   F(InitializeConstGlobal, 2, 1) \
   F(InitializeConstContextSlot, 3, 1) \
   F(OptimizeObjectForAddingMultipleProperties, 2, 1) \
   \
   /* Debugging */ \
   F(DebugPrint, 1, 1) \
   F(DebugTrace, 0, 1) \
   F(TraceEnter, 0, 1) \
@@ skipping 325 matching lines @@
 
   // This function is used in FunctionNameUsing* tests.
   static Object* FindSharedFunctionInfoInScript(Isolate* isolate,
                                                 Handle<Script> script,
                                                 int position);
 
   // Helper functions used stubs.
   static void PerformGC(Object* result);
 };
 
+
+//---------------------------------------------------------------------------
+// Constants used by interface to runtime functions.
+
+enum kDeclareGlobalsFlags {
+  kDeclareGlobalsEvalFlag = 1 << 0,
+  kDeclareGlobalsStrictModeFlag = 1 << 1,
+  kDeclareGlobalsNativeFlag = 1 << 2
+};
+
 } }  // namespace v8::internal
 
 #endif  // V8_RUNTIME_H_