Add a safe API for creating ASCII-only strings

src/factory.cc

Index: src/factory.cc
diff --git a/src/factory.cc b/src/factory.cc
index 556f2b01b793bc11c45a1c0a1f094e57b02ff835..c4c792dcc41083b50bbe41c516839a3438c8ea44 100644
--- a/src/factory.cc
+++ b/src/factory.cc
@@ -204,6 +204,16 @@ Handle<String> Factory::NewStringFromAscii(Vector<const char> string,
       String);
 }
 
+
+Handle<String> Factory::NewStringFromAsciiSafe(Vector<const char> string,
+                                           PretenureFlag pretenure) {
+  CALL_HEAP_FUNCTION(
+      isolate(),
+      isolate()->heap()->AllocateStringFromAsciiSafe(string, pretenure),
+      String);
+}
+
+
 Handle<String> Factory::NewStringFromUtf8(Vector<const char> string,
                                           PretenureFlag pretenure) {
   CALL_HEAP_FUNCTION(