Improved function entry hook coverage

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 53dca036b9ebb7b10c728e175221cb78ae4e9554..7af44cb1412a9da63b357d08358290620228aa9d 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -2575,7 +2575,14 @@ Genesis::Genesis(Isolate* isolate,
   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());