Allow constants to be deleted by reinserting them into the graph as needed.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 867fa50fca25aa30e5508edc5368d76b23c7a576..3a367e2e43155248501bd6718fc52d81ae9b21c8 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -2563,6 +2563,7 @@ bool HConstant::EmitAtUses() {
   ASSERT(IsLinked());
   if (block()->graph()->has_osr() &&
       block()->graph()->IsStandardConstant(this)) {
+    // TODO(titzer): this seems like a hack that should be fixed by custom OSR.
     return true;
   }
   if (UseCount() == 0) return true;