Experimental lexer: fix internalization and allocation of literals.

src/parser.h

Index: src/parser.h
diff --git a/src/parser.h b/src/parser.h
index e97d7c05b9573e2b6d72b01a5214dc25ca1e7b1f..c0b280c4ba70db7027994606cac6417fe71e593e 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -666,23 +666,11 @@ class Parser : public ParserBase {
   bool CheckInOrOf(bool accept_OF, ForEachStatement::VisitMode* visit_mode);
 
   Handle<String> LiteralString(PretenureFlag tenured) {
-    if (scanner().is_literal_ascii()) {
-      return isolate_->factory()->NewStringFromAscii(
-          scanner().literal_ascii_string(), tenured);
-    } else {
-      return isolate_->factory()->NewStringFromTwoByte(
-            scanner().literal_utf16_string(), tenured);
-    }
+    return scanner().GetLiteralString(tenured);
   }
 
   Handle<String> NextLiteralString(PretenureFlag tenured) {
-    if (scanner().is_next_literal_ascii()) {
-      return isolate_->factory()->NewStringFromAscii(
-          scanner().next_literal_ascii_string(), tenured);
-    } else {
-      return isolate_->factory()->NewStringFromTwoByte(
-          scanner().next_literal_utf16_string(), tenured);
-    }
+    return scanner().GetNextLiteralString(tenured);
   }
 
   Handle<String> GetSymbol();