Replace ToAsciiVector and ToUC16Vector with single function that returns a tagged value.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 176218616e2917ff93e86e8ed50013fb0cc4e053..d3cc8a62b4d8623f572937297dcb06e9f141b5c7 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -778,7 +778,7 @@ void HHasInstanceTypeAndBranch::PrintDataTo(StringStream* stream) {
 void HTypeofIsAndBranch::PrintDataTo(StringStream* stream) {
   value()->PrintNameTo(stream);
   stream->Add(" == ");
-  stream->Add(type_literal_->ToAsciiVector());
+  stream->Add(type_literal_->GetFlatContent().ToAsciiVector());
 }