[turbofan] Quit storing strings in types.

src/compiler/types.cc

Index: src/compiler/types.cc
diff --git a/src/compiler/types.cc b/src/compiler/types.cc
index 6b308232674aa7d556d26cb16fbe80d9df15b9d1..14bfdddc2f5755492dd1eaae506564d064b69d2e 100644
--- a/src/compiler/types.cc
+++ b/src/compiler/types.cc
@@ -406,6 +406,7 @@ HeapConstantType::HeapConstantType(BitsetType::bitset bitset,
                                    i::Handle<i::HeapObject> object)
     : TypeBase(kHeapConstant), bitset_(bitset), object_(object) {
   DCHECK(!object->IsHeapNumber());
+  DCHECK(!object->IsString());
 }
 
 // -----------------------------------------------------------------------------
@@ -781,6 +782,17 @@ Type* Type::NewConstant(i::Handle<i::Object> value, Zone* zone) {
     return Range(v, v, zone);
   } else if (value->IsHeapNumber()) {
     return NewConstant(value->Number(), zone);
+  } else if (value->IsString()) {
+    bitset b = BitsetType::Lub(*value);
+    DCHECK(b == BitsetType::kInternalizedString ||
+           b == BitsetType::kOtherString);
+    if (b == BitsetType::kInternalizedString) {
+      return Type::InternalizedString();
+    } else if (b == BitsetType::kOtherString) {
+      return Type::OtherString();
+    } else {
+      UNREACHABLE();
+    }
   }
   return HeapConstant(i::Handle<i::HeapObject>::cast(value), zone);
 }