Update V8 to r6768 as required by WebKit r78450

Change-Id: Ib8868ff7147a76547a8d1d85f257ebe8546a3d3f
diff --git a/src/frames.cc b/src/frames.cc
index 7f28ff1..24ea8dd 100644
--- a/src/frames.cc
+++ b/src/frames.cc
@@ -695,7 +695,7 @@
   ASSERT(frames->length() == 0);
   ASSERT(is_optimized());
 
-  int deopt_index = AstNode::kNoNumber;
+  int deopt_index = Safepoint::kNoDeoptimizationIndex;
   DeoptimizationInputData* data = GetDeoptimizationData(&deopt_index);
 
   // BUG(3243555): Since we don't have a lazy-deopt registered at
@@ -793,7 +793,7 @@
 
   SafepointEntry safepoint_entry = code->GetSafepointEntry(pc());
   *deopt_index = safepoint_entry.deoptimization_index();
-  ASSERT(*deopt_index != AstNode::kNoNumber);
+  ASSERT(*deopt_index != Safepoint::kNoDeoptimizationIndex);
 
   return DeoptimizationInputData::cast(code->deoptimization_data());
 }
@@ -803,7 +803,7 @@
   ASSERT(functions->length() == 0);
   ASSERT(is_optimized());
 
-  int deopt_index = AstNode::kNoNumber;
+  int deopt_index = Safepoint::kNoDeoptimizationIndex;
   DeoptimizationInputData* data = GetDeoptimizationData(&deopt_index);
 
   TranslationIterator it(data->TranslationByteArray(),