Update V8 to r5716 as required by WebKit r70949

Change-Id: I0d5cd05bb0427af33e5c9f6efdc209366a32bde3
diff --git a/src/assembler.cc b/src/assembler.cc
index b6efdb9..ce90dce 100644
--- a/src/assembler.cc
+++ b/src/assembler.cc
@@ -583,6 +583,12 @@
 }
 
 
+ExternalReference ExternalReference::delete_handle_scope_extensions() {
+  return ExternalReference(Redirect(FUNCTION_ADDR(
+                           HandleScope::DeleteExtensions)));
+}
+
+
 ExternalReference ExternalReference::random_uint32_function() {
   return ExternalReference(Redirect(FUNCTION_ADDR(V8::Random)));
 }
@@ -653,8 +659,8 @@
 }
 
 
-ExternalReference ExternalReference::handle_scope_extensions_address() {
-  return ExternalReference(HandleScope::current_extensions_address());
+ExternalReference ExternalReference::handle_scope_level_address() {
+  return ExternalReference(HandleScope::current_level_address());
 }