Check elimination improvement: propagation of state through phis is supported, CheckMap narrowing i…

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 2f0c86d60545223b1c92c623d5b8cae294ac74cb..f8dac3bee27017b924d75ec1c2dc70a919d6a747 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -302,6 +302,12 @@ bool HBasicBlock::Dominates(HBasicBlock* other) const {
 }
 
 
+bool HBasicBlock::EqualToOrDominates(HBasicBlock* other) const {
+  if (this == other) return true;
+  return Dominates(other);
+}
+
+
 int HBasicBlock::LoopNestingDepth() const {
   const HBasicBlock* current = this;
   int result  = (current->IsLoopHeader()) ? 1 : 0;