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

vm/exceptions.cc

Index: vm/exceptions.cc
===================================================================
--- vm/exceptions.cc	(revision 16583)
+++ vm/exceptions.cc	(working copy)
@@ -393,58 +393,58 @@
 
 RawObject* Exceptions::Create(ExceptionType type, const Array& arguments) {
   Library& library = Library::Handle();
-  String& class_name = String::Handle();
+  const String* class_name = NULL;
   switch (type) {
     case kNone:
       UNREACHABLE();
       break;
     case kRange:
       library = Library::CoreLibrary();
-      class_name = Symbols::New("RangeError");
+      class_name = &Symbols::RangeError();
       break;
     case kArgument:
       library = Library::CoreLibrary();
-      class_name = Symbols::New("ArgumentError");
+      class_name = &Symbols::ArgumentError();
       break;
     case kNoSuchMethod:
       library = Library::CoreLibrary();
-      class_name = Symbols::New("NoSuchMethodError");
+      class_name = &Symbols::NoSuchMethodError();
       break;
     case kFormat:
       library = Library::CoreLibrary();
-      class_name = Symbols::New("FormatException");
+      class_name = &Symbols::FormatException();
       break;
     case kStackOverflow:
       library = Library::CoreLibrary();
-      class_name = Symbols::New("StackOverflowError");
+      class_name = &Symbols::StackOverflowError();
       break;
     case kOutOfMemory:
       library = Library::CoreLibrary();
-      class_name = Symbols::New("OutOfMemoryError");
+      class_name = &Symbols::OutOfMemoryError();
       break;
     case kInternalError:
       library = Library::CoreLibrary();
-      class_name = Symbols::New("InternalError");
+      class_name = &Symbols::InternalError();
       break;
     case kNullThrown:
       library = Library::CoreLibrary();
-      class_name = Symbols::New("NullThrownError");
+      class_name = &Symbols::NullThrownError();
       break;
     case kIllegalJSRegExp:
       library = Library::CoreLibrary();
-      class_name = Symbols::New("IllegalJSRegExpException");
+      class_name = &Symbols::IllegalJSRegExpException();
       break;
     case kIsolateSpawn:
       library = Library::IsolateLibrary();
-      class_name = Symbols::New("IsolateSpawnException");
+      class_name = &Symbols::IsolateSpawnException();
       break;
     case kIsolateUnhandledException:
       library = Library::IsolateLibrary();
-      class_name = Symbols::New("IsolateUnhandledException");
+      class_name = &Symbols::IsolateUnhandledException();
       break;
   }
 
-  return DartLibraryCalls::ExceptionCreate(library, class_name, arguments);
+  return DartLibraryCalls::ExceptionCreate(library, *class_name, arguments);
 }
 
 }  // namespace dart