Update V8 to r6768 as required by WebKit r78450

Change-Id: Ib8868ff7147a76547a8d1d85f257ebe8546a3d3f
diff --git a/test/cctest/test-debug.cc b/test/cctest/test-debug.cc
index b9f6038..441aae6 100644
--- a/test/cctest/test-debug.cc
+++ b/test/cctest/test-debug.cc
@@ -997,7 +997,7 @@
   CheckDebugBreakFunction(&env,
                           "function f2(){x=1;}", "f2",
                           0,
-                          v8::internal::RelocInfo::CODE_TARGET,
+                          v8::internal::RelocInfo::CODE_TARGET_CONTEXT,
                           Builtins::builtin(Builtins::StoreIC_DebugBreak));
   CheckDebugBreakFunction(&env,
                           "function f3(){var a=x;}", "f3",