[crankshaft] Remove useless --optimize-for-in flag.

src/crankshaft/hydrogen.cc

Index: src/crankshaft/hydrogen.cc
diff --git a/src/crankshaft/hydrogen.cc b/src/crankshaft/hydrogen.cc
index 0fa2df566d556ec94ca0a49e1b13b5dc1b0cc4be..c7185c98f2ca2696a90278ca8efa3318ccdc5352 100644
--- a/src/crankshaft/hydrogen.cc
+++ b/src/crankshaft/hydrogen.cc
@@ -5290,10 +5290,6 @@ void HOptimizedGraphBuilder::VisitForInStatement(ForInStatement* stmt) {
   DCHECK(current_block() != NULL);
   DCHECK(current_block()->HasPredecessor());
 
-  if (!FLAG_optimize_for_in) {
-    return Bailout(kForInStatementOptimizationIsDisabled);
-  }
-
   if (!stmt->each()->IsVariableProxy() ||
       !stmt->each()->AsVariableProxy()->var()->IsStackLocal()) {
     return Bailout(kForInStatementWithNonLocalEachVariable);