Fix try-finally for dead AST-branches in TurboFan.

src/compiler/ast-graph-builder.cc

 // Copyright 2014 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/ast-graph-builder.h"
 
 #include "src/compiler.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/linkage.h"
@@ skipping 1176 matching lines @@
   // that is intercepting 'throw' control commands.
   try_control.BeginTry();
   {
     ControlScopeForCatch scope(this, &try_control);
     Visit(stmt->try_block());
   }
   try_control.EndTry();
 
   // Create a catch scope that binds the exception.
   Node* exception = try_control.GetExceptionNode();
-  if (exception == NULL) exception = jsgraph()->NullConstant();
   Unique<String> name = MakeUnique(stmt->variable()->name());
   const Operator* op = javascript()->CreateCatchContext(name);
   Node* context = NewNode(op, exception, GetFunctionClosure());
   PrepareFrameState(context, BailoutId::None());
   ContextScope scope(this, stmt->scope(), context);
   DCHECK(stmt->scope()->declarations()->is_empty());
 
   // Evaluate the catch-block.
   Visit(stmt->catch_block());
   try_control.EndCatch();
@@ skipping 1924 matching lines @@
     Node* dead_node = graph()->NewNode(common()->Dead());
     dead_control_.set(dead_node);
     return dead_node;
   }
   return dead_control_.get();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8