Upgrade V8 to 5.1.281.57  DO NOT MERGE

FPIIM-449

Change-Id: Id981b686b4d587ac31697662eb98bb34be42ad90
(cherry picked from commit 3b9bc31999c9787eb726ecdbfd5796bfdec32a18)
diff --git a/src/compiler/branch-elimination.h b/src/compiler/branch-elimination.h
index a7ac926..7abeeca 100644
--- a/src/compiler/branch-elimination.h
+++ b/src/compiler/branch-elimination.h
@@ -11,6 +11,8 @@
 namespace internal {
 namespace compiler {
 
+// Forward declarations.
+class CommonOperatorBuilder;
 class JSGraph;
 
 
@@ -73,6 +75,7 @@
   };
 
   Reduction ReduceBranch(Node* node);
+  Reduction ReduceDeoptimizeConditional(Node* node);
   Reduction ReduceIf(Node* node, bool is_true_branch);
   Reduction ReduceLoop(Node* node);
   Reduction ReduceMerge(Node* node);
@@ -84,7 +87,11 @@
                              const ControlPathConditions* conditions);
 
   Node* dead() const { return dead_; }
+  Graph* graph() const;
+  JSGraph* jsgraph() const { return jsgraph_; }
+  CommonOperatorBuilder* common() const;
 
+  JSGraph* const jsgraph_;
   PathConditionsForControlNodes node_conditions_;
   Zone* zone_;
   Node* dead_;