[turbofan] Check node inputs for nullptr even in release builds

Change-Id: I626e26fa2e1486365c858f3fc616422199242f5b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1588422
Auto-Submit: Georg Neis <neis@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61162}

src/compiler/node.cc

@@ -56,7 +56,6 @@ Node* Node::New(Zone* zone, NodeId id, const Operator* op, int input_count,
   Node* node;
   bool is_inline;
 
-#if DEBUG
   // Verify that none of the inputs are {nullptr}.
   for (int i = 0; i < input_count; i++) {
     if (inputs[i] == nullptr) {
@@ -64,7 +63,6 @@ Node* Node::New(Zone* zone, NodeId id, const Operator* op, int input_count,
             op->mnemonic(), i);
     }
   }
-#endif
 
   if (input_count > kMaxInlineCapacity) {
     // Allocate out-of-line inputs.