[Turbofan] Re-enable single splinter.

src/compiler/js-native-context-specialization.cc

 // Copyright 2015 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.
 
 #include "src/compiler/js-native-context-specialization.h"
 
 #include "src/accessors.h"
 #include "src/compilation-dependencies.h"
 #include "src/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
@@ skipping 590 matching lines @@
   }
 
   // Collect the fallthru control as final "exit" control.
   exit_controls.push_back(fallthrough_control);
 
 // TODO(bmeurer/mtrofin): Splintering cannot currently deal with deferred
 // blocks that contain only a single non-deoptimize instruction (i.e. a
 // jump). Generating a single Merge here, which joins all the deoptimizing
 // controls would generate a lot of these basic blocks, however. So this
 // is disabled for now until splintering is fixed.
-#if 0
+#if 1
   // Generate the single "exit" point, where we get if either all map/instance
   // type checks failed, or one of the assumptions inside one of the cases
   // failes (i.e. failing prototype chain check).
   // TODO(bmeurer): Consider falling back to IC here if deoptimization is
   // disabled.
   int const exit_control_count = static_cast<int>(exit_controls.size());
   Node* exit_control =
       (exit_control_count == 1)
           ? exit_controls.front()
           : graph()->NewNode(common()->Merge(exit_control_count),
@@ skipping 87 matching lines @@
 }
 
 
 SimplifiedOperatorBuilder* JSNativeContextSpecialization::simplified() const {
   return jsgraph()->simplified();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8