[turbofan] Remove unused BuildLoadGlobalProxy from AstGraphBuilder.

src/compiler/ast-graph-builder.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_AST_GRAPH_BUILDER_H_
 #define V8_COMPILER_AST_GRAPH_BUILDER_H_
 
 #include "src/ast.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/liveness-analyzer.h"
@@ skipping 283 matching lines @@
 
   // Builders for global variable loads and stores.
   Node* BuildGlobalLoad(Handle<Name> name, const VectorSlotPair& feedback,
                         TypeofMode typeof_mode);
   Node* BuildGlobalStore(Handle<Name> name, Node* value,
                          const VectorSlotPair& feedback);
 
   // Builders for accessing the function context.
   Node* BuildLoadGlobalObject();
   Node* BuildLoadNativeContextField(int index);
-  Node* BuildLoadGlobalProxy();
   Node* BuildLoadFeedbackVector();
 
   // Builder for accessing a (potentially immutable) object field.
   Node* BuildLoadObjectField(Node* object, int offset);
   Node* BuildLoadImmutableObjectField(Node* object, int offset);
 
   // Builders for accessing external references.
   Node* BuildLoadExternal(ExternalReference ref, MachineType type);
   Node* BuildStoreExternal(ExternalReference ref, MachineType type, Node* val);
 
@@ skipping 257 matching lines @@
 
   // Prepare environment to be used as loop header.
   void PrepareForLoop(BitVector* assigned, bool is_osr = false);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_AST_GRAPH_BUILDER_H_