[turbofan] Tentative fix for ControlEquivalence crasher.

The ControlEquivalence cannot deal with new nodes inserted by the
Scheduler due to Node splitting. Rather when the ControlEquivalence
sees such a new Node, it'll likely crash on an out-of-bounds access.

This is a speculative fix to make the crash disappear, as there's no
100% reliable repro currently.

BUG=chromium:629398
TBR=jochen@chromium.org

Review-Url: https://codereview.chromium.org/2611603002
Cr-Commit-Position: refs/heads/master@{#42016}

src/compiler/control-equivalence.h

@@ -124,7 +124,11 @@ class V8_EXPORT_PRIVATE ControlEquivalence final
   void DetermineParticipation(Node* exit);
 
  private:
-  NodeData* GetData(Node* node) { return &node_data_[node->id()]; }
+  NodeData* GetData(Node* node) {
+    size_t const index = node->id();
+    if (index >= node_data_.size()) node_data_.resize(index + 1, EmptyData());
+    return &node_data_[index];
+  }
   int NewClassNumber() { return class_number_++; }
   int NewDFSNumber() { return dfs_number_++; }