[turbofan] Remove overly restrictive DCHECK.

The dead code elimination in SimplifiedLowering can eliminate pure nodes
if they don't have value uses. But some of those can indeed have control
inputs, i.e. Phi nodes do of course have a control input.

R=jarin@chromium.org
BUG=chromium:630923

Review-Url: https://codereview.chromium.org/2177133002
Cr-Commit-Position: refs/heads/master@{#37995}

src/compiler/simplified-lowering.cc

@@ -2445,7 +2445,6 @@ class RepresentationSelector {
       Node* effect = NodeProperties::GetEffectInput(node);
       ReplaceEffectControlUses(node, effect, control);
     } else {
-      DCHECK_EQ(0, node->op()->ControlInputCount());
       DCHECK_EQ(0, node->op()->EffectInputCount());
       DCHECK_EQ(0, node->op()->ControlOutputCount());
       DCHECK_EQ(0, node->op()->EffectOutputCount());

test/mjsunit/regress/regress-crbug-630923.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax
+
+var o = {};
+function bar(o) {
+  return 1 + (o.t ? 1 : 2);
+}
+function foo() {
+  bar(o);
+}
+foo();
+%OptimizeFunctionOnNextCall(foo);
+foo();