[turbofan] Ship TurboFan with spread expressions.

This triggers TurboFan whenever functions containing spread expressions
of any kind are marked for optimization. Note that this increases the
set of functions being eligible for optimization.

R=rossberg@chromium.org,hablich@chromium.org

Review URL: https://codereview.chromium.org/1461603002

Cr-Commit-Position: refs/heads/master@{#32083}

src/ast-numbering.cc

@@ -373,7 +373,7 @@ void AstNumberingVisitor::VisitCompareOperation(CompareOperation* node) {
 
 void AstNumberingVisitor::VisitSpread(Spread* node) {
   IncrementNodeCount();
-  DisableOptimization(kSpread);
+  DisableCrankshaft(kSpread);
   Visit(node->expression());
 }