Print HAllocate flags in --trace-hydrogen.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index d3eda765a70035d375d27ff6f717ed6296695a9d..b255cd2e2ad7894261d8ed09551927c1c7c54a86 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -3730,7 +3730,13 @@ void HAllocate::HandleSideEffectDominator(GVNFlag side_effect,
 
 void HAllocate::PrintDataTo(StringStream* stream) {
   size()->PrintNameTo(stream);
-  if (!IsNewSpaceAllocation()) stream->Add(" (pretenure)");
+  stream->Add(" (");
+  if (IsNewSpaceAllocation()) stream->Add("N");
+  if (IsOldPointerSpaceAllocation()) stream->Add("P");
+  if (IsOldDataSpaceAllocation()) stream->Add("D");
+  if (MustAllocateDoubleAligned()) stream->Add("A");
+  if (MustPrefillWithFiller()) stream->Add("F");
+  stream->Add(")");
 }