Improved function entry hook coverage

src/bootstrapper.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 2557 matching lines @@
   // Before creating the roots we must save the context and restore it
   // on all function exits.
   SaveContext saved_context(isolate);
 
   // During genesis, the boilerplate for stack overflow won't work until the
   // environment has been at least partially initialized. Add a stack check
   // before entering JS code to catch overflow early.
   StackLimitCheck check(isolate);
   if (check.HasOverflowed()) return;
 
-  native_context_ = Snapshot::NewContextFromSnapshot();
+  // We can only de-serialize a context if the isolate was initialized from
+  // a snapshot. Otherwise we have to build the context from scratch.
+  if (isolate->initialized_from_snapshot()) {
+    native_context_ = Snapshot::NewContextFromSnapshot();
+  } else {
+    native_context_ = Handle<Context>();
+  }
+
   if (!native_context().is_null()) {
     AddToWeakNativeContextList(*native_context());
     isolate->set_context(*native_context());
     isolate->counters()->contexts_created_by_snapshot()->Increment();
     Handle<GlobalObject> inner_global;
     Handle<JSGlobalProxy> global_proxy =
         CreateNewGlobals(global_template,
                          global_object,
                          &inner_global);
 
@@ skipping 51 matching lines @@
   return from + sizeof(NestingCounterType);
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   ASSERT(!IsActive());
 }
 
 } }  // namespace v8::internal