Prevent flushing of code that was set with %SetCode.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 792a14296c4964fce21b15df2855055db6d0d6b8..774e961d5b4529f0c90a2aee9436a18e18bbd309 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -2498,6 +2498,13 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_SetCode) {
     return Failure::Exception();
   }
 
+  // Mark both, the source and the target, as un-flushable because the
+  // shared unoptimized code makes them impossible to enqueue in a list.
+  ASSERT(target_shared->code()->gc_metadata() == NULL);
+  ASSERT(source_shared->code()->gc_metadata() == NULL);
+  target_shared->set_dont_flush(true);
+  source_shared->set_dont_flush(true);
+
   // Set the code, scope info, formal parameter count, and the length
   // of the target shared function info.  Set the source code of the
   // target function to undefined.  SetCode is only used for built-in