[turbofan] Narrow type of Phis during JSTypedLowering.

src/compiler/js-typed-lowering.h

 // 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.
 
 #ifndef V8_COMPILER_JS_TYPED_LOWERING_H_
 #define V8_COMPILER_JS_TYPED_LOWERING_H_
 
 #include "src/base/flags.h"
 #include "src/compiler/graph-reducer.h"
 #include "src/compiler/opcodes.h"
@@ skipping 62 matching lines @@
   Reduction ReduceJSForInNext(Node* node);
   Reduction ReduceJSForInStep(Node* node);
   Reduction ReduceJSGeneratorStore(Node* node);
   Reduction ReduceJSGeneratorRestoreContinuation(Node* node);
   Reduction ReduceJSGeneratorRestoreRegister(Node* node);
   Reduction ReduceCheckMaps(Node* node);
   Reduction ReduceCheckString(Node* node);
   Reduction ReduceLoadField(Node* node);
   Reduction ReduceNumberRoundop(Node* node);
   Reduction ReduceSelect(Node* node);
+  Reduction ReducePhi(Node* node);
   Reduction ReduceNumberBinop(Node* node);
   Reduction ReduceInt32Binop(Node* node);
   Reduction ReduceUI32Shift(Node* node, Signedness signedness);
 
   Factory* factory() const;
   Graph* graph() const;
   JSGraph* jsgraph() const { return jsgraph_; }
   Isolate* isolate() const;
   JSOperatorBuilder* javascript() const;
   CommonOperatorBuilder* common() const;
@@ skipping 12 matching lines @@
   TypeCache const& type_cache_;
 };
 
 DEFINE_OPERATORS_FOR_FLAGS(JSTypedLowering::Flags)
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_JS_TYPED_LOWERING_H_