Allow Script::FindSharedFunctionInfo to return toplevel functions

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index 7c58f9ef91b4d3a599eaffff2d1257a4f432fbb0..fdb41e732bdd1cbd8844cb87e688696ad3522b83 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -1570,6 +1570,7 @@ Handle<SharedFunctionInfo> Compiler::GetSharedFunctionInfo(
   // unless we already have code with debut break slots.
   Handle<SharedFunctionInfo> existing;
   if (maybe_existing.ToHandle(&existing) && existing->is_compiled()) {
+    DCHECK(!existing->is_toplevel());
     if (!outer_info->is_debug() || existing->HasDebugCode()) {
       return existing;
     }