Update V8 to r6768 as required by WebKit r78450

Change-Id: Ib8868ff7147a76547a8d1d85f257ebe8546a3d3f
diff --git a/src/variables.cc b/src/variables.cc
index 7f580fc..fa7ce1b 100644
--- a/src/variables.cc
+++ b/src/variables.cc
@@ -112,12 +112,12 @@
   : scope_(scope),
     name_(name),
     mode_(mode),
-    is_valid_LHS_(is_valid_LHS),
     kind_(kind),
     local_if_not_shadowed_(NULL),
+    rewrite_(NULL),
+    is_valid_LHS_(is_valid_LHS),
     is_accessed_from_inner_scope_(false),
-    is_used_(false),
-    rewrite_(NULL) {
+    is_used_(false) {
   // names must be canonicalized for fast equality checks
   ASSERT(name->IsSymbol());
 }