Guard against undefined fields in global context.

src/assembler.cc

 // Copyright (c) 2011 Sun Microsystems Inc.
 // All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 // - Redistributions of source code must retain the above copyright notice,
 // this list of conditions and the following disclaimer.
 //
@@ skipping 799 matching lines @@
 }
 
 
 ExternalReference ExternalReference::compute_output_frames_function(
     Isolate* isolate) {
   return ExternalReference(
       Redirect(isolate, FUNCTION_ADDR(Deoptimizer::ComputeOutputFrames)));
 }
 
 
-ExternalReference ExternalReference::global_contexts_list(Isolate* isolate) {
-  return ExternalReference(isolate->heap()->global_contexts_list_address());
-}
-
-
 ExternalReference ExternalReference::keyed_lookup_cache_keys(Isolate* isolate) {
   return ExternalReference(isolate->keyed_lookup_cache()->keys_address());
 }
 
 
 ExternalReference ExternalReference::keyed_lookup_cache_field_offsets(
     Isolate* isolate) {
   return ExternalReference(
       isolate->keyed_lookup_cache()->field_offsets_address());
 }
@@ skipping 418 matching lines @@
     assembler_->RecordRelocInfo(RelocInfo::POSITION, state_.current_position);
     state_.written_position = state_.current_position;
     written = true;
   }
 
   // Return whether something was written.
   return written;
 }
 
 } }  // namespace v8::internal