Reland of "Store SharedFunctionInfos of a Script in a FixedArray indexed by their ID"

src/runtime/runtime-function.cc

Index: src/runtime/runtime-function.cc
diff --git a/src/runtime/runtime-function.cc b/src/runtime/runtime-function.cc
index 8cf21c0e8528d7adafbf3209cf8b1705c0ca181c..7413f8750ae5d69648f15ac1b3dc04ac198daa60 100644
--- a/src/runtime/runtime-function.cc
+++ b/src/runtime/runtime-function.cc
@@ -204,8 +204,13 @@ RUNTIME_FUNCTION(Runtime_SetCode) {
   target_shared->set_native(was_native);
   target_shared->set_profiler_ticks(source_shared->profiler_ticks());
   target_shared->set_function_literal_id(source_shared->function_literal_id());
-  SharedFunctionInfo::SetScript(
-      target_shared, Handle<Object>(source_shared->script(), isolate));
+
+  Handle<Object> source_script(source_shared->script(), isolate);
+  if (source_script->IsScript()) {
+    SharedFunctionInfo::SetScript(source_shared,
+                                  isolate->factory()->undefined_value());
+  }
+  SharedFunctionInfo::SetScript(target_shared, source_script);
 
   // Set the code of the target function.
   target->ReplaceCode(source_shared->code());