Convert all symbols accessor to return read only handles so that it is not necessary to create a ne…

lib/integers.cc

Index: lib/integers.cc
===================================================================
--- lib/integers.cc	(revision 16583)
+++ lib/integers.cc	(working copy)
@@ -185,8 +185,7 @@
 
 DEFINE_NATIVE_ENTRY(Integer_parse, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(String, value, arguments->NativeArgAt(0));
-  const String& dummy_key = String::Handle(Symbols::Empty());
-  Scanner scanner(value, dummy_key);
+  Scanner scanner(value, Symbols::Empty());
   const Scanner::GrowableTokenStream& tokens = scanner.GetStream();
   String* int_string;
   bool is_positive;
@@ -198,7 +197,7 @@
       return Integer::New(*int_string);
     }
     String& temp = String::Handle();
-    temp = String::Concat(String::Handle(Symbols::New("-")), *int_string);
+    temp = String::Concat(Symbols::Dash(), *int_string);
     return Integer::New(temp);
   }