- Reintroduce a library privacy disabling option.

vm/scanner.cc

Index: vm/scanner.cc
===================================================================
--- vm/scanner.cc	(revision 4985)
+++ vm/scanner.cc	(working copy)
@@ -13,6 +13,7 @@
 
 namespace dart {
 
+DEFINE_FLAG(bool, disable_privacy, false, "Disable library privacy.");
 DEFINE_FLAG(bool, print_tokens, false, "Print scanned tokens.");
 
 void Scanner::InitKeywordTable() {
@@ -290,7 +291,7 @@
   current_token_.kind = Token::kIDENT;
   String& literal =
       String::ZoneHandle(String::NewSymbol(source_, ident_pos, ident_length));
-  if (ident_char0 == kPrivateIdentifierStart) {
+  if ((ident_char0 == kPrivateIdentifierStart) && !FLAG_disable_privacy) {
     // Private identifiers are mangled on a per script basis.
     literal = String::Concat(literal, private_key_);
     literal = String::NewSymbol(literal);