[compiler] Generalize JSContextSpecialization.

src/compiler/node-properties.h

 // Copyright 2013 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_NODE_PROPERTIES_H_
 #define V8_COMPILER_NODE_PROPERTIES_H_
 
 #include "src/compiler/node.h"
 #include "src/compiler/types.h"
 #include "src/globals.h"
@@ skipping 114 matching lines @@
 
   // ---------------------------------------------------------------------------
   // Context.
 
   // Try to retrieve the specialization context from the given {node},
   // optionally utilizing the knowledge about the (outermost) function
   // {context}.
   static MaybeHandle<Context> GetSpecializationContext(
       Node* node, MaybeHandle<Context> context = MaybeHandle<Context>());
 
+  // Walk up the context chain from the given {node} until we reduce the {depth}
+  // to 0 or hit a node that does not extend the context chain ({depth} will be
+  // updated accordingly).
+  static Node* GetOuterContext(Node* node, size_t* depth);
+
   // ---------------------------------------------------------------------------
   // Type.
 
   static bool IsTyped(Node* node) { return node->type() != nullptr; }
   static Type* GetType(Node* node) {
     DCHECK(IsTyped(node));
     return node->type();
   }
   static Type* GetTypeOrAny(Node* node);
   static void SetType(Node* node, Type* type) {
     DCHECK_NOT_NULL(type);
     node->set_type(type);
   }
   static void RemoveType(Node* node) { node->set_type(nullptr); }
   static bool AllValueInputsAreTyped(Node* node);
 
  private:
   static inline bool IsInputRange(Edge edge, int first, int count);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_NODE_PROPERTIES_H_