Revert of Remove Scope::scope_uses_this_ flag

src/compiler/ast-graph-builder.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/ast-graph-builder.h"
 
 #include "src/compiler.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/js-type-feedback.h"
@@ skipping 2643 matching lines @@
   return value;
 }
 
 
 Node* AstGraphBuilder::BuildPatchReceiverToGlobalProxy(Node* receiver) {
   // Sloppy mode functions and builtins need to replace the receiver with the
   // global proxy when called as functions (without an explicit receiver
   // object). Otherwise there is nothing left to do here.
   if (is_strict(language_mode()) || info()->is_native()) return receiver;
 
-  // There is no need to perform patching if the receiver will never be used.
+  // There is no need to perform patching if the receiver is never used. Note
+  // that scope predicates are purely syntactical, a call to eval might still
+  // inspect the receiver value.
   if (!info()->MayUseThis()) return receiver;
 
   IfBuilder receiver_check(this);
   Node* undefined = jsgraph()->UndefinedConstant();
   Node* check = NewNode(javascript()->StrictEqual(), receiver, undefined);
   receiver_check.If(check);
   receiver_check.Then();
   Node* proxy = BuildLoadGlobalProxy();
   environment()->Push(proxy);
   receiver_check.Else();
@@ skipping 924 matching lines @@
     // Phi does not exist yet, introduce one.
     value = NewPhi(inputs, value, control);
     value->ReplaceInput(inputs - 1, other);
   }
   return value;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8