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

src/runtime.h

Index: src/runtime.h
diff --git a/src/runtime.h b/src/runtime.h
index 91a19dfd453d592aec932b884862a06e3ff14ce0..7db26db90d5f723e797e78becaf2a20dc50dc9f0 100644
--- a/src/runtime.h
+++ b/src/runtime.h
@@ -317,7 +317,7 @@ namespace internal {
   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) \
@@ -663,6 +663,16 @@ class Runtime : public AllStatic {
   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_