[turbofan] Added the RoundInt64ToFloat64 instruction to TurboFan.

src/compiler/typer.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/typer.h"
 
 #include "src/base/flags.h"
 #include "src/bootstrapper.h"
 #include "src/compilation-dependencies.h"
 #include "src/compiler/common-operator.h"
@@ skipping 1960 matching lines @@
   return Type::Intersect(Type::Unsigned32(), Type::UntaggedUnsigned32(),
                          zone());
 }
 
 
 Type* Typer::Visitor::TypeChangeInt32ToFloat64(Node* node) {
   return Type::Intersect(Type::Signed32(), Type::UntaggedFloat64(), zone());
 }
 
 
+Type* Typer::Visitor::TypeChangeInt64ToFloat64(Node* node) {
+  return Type::Intersect(Type::Signed64(), Type::UntaggedFloat64(), zone());
+}
+
+
 Type* Typer::Visitor::TypeChangeInt32ToInt64(Node* node) {
   return Type::Internal();
 }
 
 
 Type* Typer::Visitor::TypeChangeUint32ToFloat64(Node* node) {
   return Type::Intersect(Type::Unsigned32(), Type::UntaggedFloat64(), zone());
 }
 
 
@@ skipping 192 matching lines @@
   }
   if (Type::IsInteger(*value)) {
     return Type::Range(value->Number(), value->Number(), zone());
   }
   return Type::Constant(value, zone());
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8