Improve error message for some unresolved identifiers

runtime/vm/code_generator_x64.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/code_generator.h"
 
 #include "lib/error.h"
@@ skipping 890 matching lines @@
   }
   if (IsResultNeeded(node)) {
     __ pushq(RAX);
   }
 }
 
 
 void CodeGenerator::VisitPrimaryNode(PrimaryNode* node) {
   // PrimaryNodes are temporary during parsing.
   ErrorMsg(node->token_index(),
-      "Unexpected primary node: %s", node->primary().ToCString());
+      "Unresolved identifier '%s'", node->primary().ToCString());
 }
 
 
 void CodeGenerator::VisitCloneContextNode(CloneContextNode *node) {
   const Context& result = Context::ZoneHandle();
   __ PushObject(result);
   __ pushq(CTX);
   GenerateCallRuntime(node->id(),
       node->token_index(), kCloneContextRuntimeEntry);
   __ popq(RAX);
@@ skipping 1876 matching lines @@
   const Error& error = Error::Handle(
       Parser::FormatError(script, token_index, "Error", format, args));
   va_end(args);
   Isolate::Current()->long_jump_base()->Jump(1, error);
   UNREACHABLE();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64