[compiler] Generalize JSContextSpecialization.

src/compiler/node-properties.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/node-properties.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/js-operator.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/operator-properties.h"
@@ skipping 321 matching lines @@
       break;
     }
     default:
       break;
   }
   return MaybeHandle<Context>();
 }
 
 
 // static
+Node* NodeProperties::GetOuterContext(Node* node, size_t* depth) {
+  Node* context = NodeProperties::GetContextInput(node);
+  while (*depth > 0 &&
+         IrOpcode::IsContextChainExtendingOpcode(context->opcode())) {
+    context = NodeProperties::GetContextInput(context);
+    (*depth)--;
+  }
+  return context;
+}
+
+// static
 Type* NodeProperties::GetTypeOrAny(Node* node) {
   return IsTyped(node) ? node->type() : Type::Any();
 }
 
 
 // static
 bool NodeProperties::AllValueInputsAreTyped(Node* node) {
   int input_count = node->op()->ValueInputCount();
   for (int index = 0; index < input_count; ++index) {
     if (!IsTyped(GetValueInput(node, index))) return false;
   }
   return true;
 }
 
 
 // static
 bool NodeProperties::IsInputRange(Edge edge, int first, int num) {
   if (num == 0) return false;
   int const index = edge.index();
   return first <= index && index < first + num;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8