[turbofan] Check for dead node in the common operator reducer.

test/mjsunit/regress/regress-556543.js

Index: test/mjsunit/regress/regress-556543.js
diff --git a/test/mjsunit/array-push12.js b/test/mjsunit/regress/regress-556543.js
similarity index 56%
copy from test/mjsunit/array-push12.js
copy to test/mjsunit/regress/regress-556543.js
index f4c15b484b41197c9007113ecf8f91fe909cc5d3..9e9bedd6f553c4701164fd1dac66f4f2df13324d 100644
--- a/test/mjsunit/array-push12.js
+++ b/test/mjsunit/regress/regress-556543.js
@@ -4,20 +4,14 @@
 
 // Flags: --allow-natives-syntax
 
-var a = [];
-for (var i = -20; i < 0; ++i) {
-  a[i] = 0;
-}
-
-function g() {
-    [].push.apply(a, arguments);
-}
-
 function f() {
-  g();
+  for (var __v_2 = 0; __v_2 < __v_5; ++__v_2) {
+    for (var __v_5 = 0; __v_3 < 1; ++__v_8) {
+      if (true || 0 > -6) continue;
+      for (var __v_3 = 0; __v_3 < 1; ++__v_3) {
+      }
+    }
+  }
 }
-
-g();
-g();
 %OptimizeFunctionOnNextCall(f);
 f();