Update V8 to r6768 as required by WebKit r78450

Change-Id: Ib8868ff7147a76547a8d1d85f257ebe8546a3d3f
diff --git a/src/runtime.h b/src/runtime.h
index dbd8d64..fb2ff93 100644
--- a/src/runtime.h
+++ b/src/runtime.h
@@ -237,8 +237,8 @@
   \
   /* Eval */ \
   F(GlobalReceiver, 1, 1) \
-  F(ResolvePossiblyDirectEval, 3, 2) \
-  F(ResolvePossiblyDirectEvalNoLookup, 3, 2) \
+  F(ResolvePossiblyDirectEval, 4, 2) \
+  F(ResolvePossiblyDirectEvalNoLookup, 4, 2) \
   \
   F(SetProperty, -1 /* 3 or 4 */, 1) \
   F(DefineOrRedefineDataProperty, 4, 1) \
@@ -284,7 +284,7 @@
   F(NewContext, 1, 1) \
   F(PushContext, 1, 1) \
   F(PushCatchContext, 1, 1) \
-  F(LookupContext, 2, 1) \
+  F(DeleteContextSlot, 2, 1) \
   F(LoadContextSlot, 2, 2) \
   F(LoadContextSlotNoReferenceError, 2, 2) \
   F(StoreContextSlot, 3, 1) \
@@ -310,6 +310,13 @@
   /* Cache suport */ \
   F(GetFromCache, 2, 1) \
   \
+  /* Message objects */ \
+  F(NewMessageObject, 2, 1) \
+  F(MessageGetType, 1, 1) \
+  F(MessageGetArguments, 1, 1) \
+  F(MessageGetStartPosition, 1, 1) \
+  F(MessageGetScript, 1, 1) \
+  \
   /* Pseudo functions - handled as macros by parser */ \
   F(IS_VAR, 1, 1)