[heap] Unprotect huge free list nodes for code allocation.

Bug: chromium:774108
Change-Id: I640a4f0f17244ee77fa5480ec9faa773310b9caf
Reviewed-on: https://chromium-review.googlesource.com/958907Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51880}

src/heap/spaces.cc

@@ -2736,6 +2736,11 @@ FreeSpace* FreeListCategory::SearchForNodeInList(size_t minimum_size,
         set_top(cur_node->next());
       }
       if (prev_non_evac_node != nullptr) {
+        MemoryChunk* chunk =
+            MemoryChunk::FromAddress(prev_non_evac_node->address());
+        if (chunk->owner()->identity() == CODE_SPACE) {
+          chunk->heap()->UnprotectAndRegisterMemoryChunk(chunk);
+        }
         prev_non_evac_node->set_next(cur_node->next());
       }
       *node_size = size;