Workarround for: Chrome dev tools crashes when taking a heap snapshot of Docs offline shared worker.

src/profile-generator.cc

 // Copyright 2012 the V8 project authors. 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.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2674 matching lines @@
   Handle<String> url_string =
       isolate->factory()->NewStringFromAscii(CStrVector("URL"));
   const char** urls = NewArray<const char*>(enumerator.count());
   for (int i = 0, l = enumerator.count(); i < l; ++i) {
     urls[i] = NULL;
     HandleScope scope;
     Handle<JSGlobalObject> global_obj = enumerator.at(i);
     Object* obj_document;
     if (global_obj->GetProperty(*document_string)->ToObject(&obj_document) &&
         obj_document->IsJSObject()) {
+      // FixMe: Workaround: SharedWorker's current Isolate has NULL context.
+      // As result GetProperty(*url_string) will crash.
+      if (!Isolate::Current()->context() && obj_document->IsJSGlobalProxy())
+        continue;
       JSObject* document = JSObject::cast(obj_document);
       Object* obj_url;
       if (document->GetProperty(*url_string)->ToObject(&obj_url) &&
           obj_url->IsString()) {
         urls[i] = collection_->names()->GetName(String::cast(obj_url));
       }
     }
   }
 
   AssertNoAllocation no_allocation;
@@ skipping 852 matching lines @@
 
 
 void HeapSnapshotJSONSerializer::SortHashMap(
     HashMap* map, List<HashMap::Entry*>* sorted_entries) {
   for (HashMap::Entry* p = map->Start(); p != NULL; p = map->Next(p))
     sorted_entries->Add(p);
   sorted_entries->Sort(SortUsingEntryValue);
 }
 
 } }  // namespace v8::internal