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

src/profile-generator.cc

Index: src/profile-generator.cc
diff --git a/src/profile-generator.cc b/src/profile-generator.cc
index ca19f4aaaffea68b8a12e0764086bfa09ec5e06a..a3143bea5b8d46aac2a03bf3e696e28cc61740e6 100644
--- a/src/profile-generator.cc
+++ b/src/profile-generator.cc
@@ -2692,6 +2692,10 @@ void V8HeapExplorer::TagGlobalObjects() {
     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) &&