[proxies] use [[GetPrototypeOf]] trap in for-in

test/mjsunit/for-in-opt.js

 // 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.
 
 // Flags: --harmony-proxies --allow-natives-syntax --expose-debug-as debug
 
 "use strict";
 
 // Test non-JSObject receiver.
 function f(o) {
   var result = [];
   for (var i in o) {
     result.push(i);
   }
   return result;
 }
 
 assertEquals(["0"], f("a"));
 assertEquals(["0"], f("a"));
 
 %OptimizeFunctionOnNextCall(f);
 assertEquals(["0","1","2"], f("bla"));
 
 // Test the lazy deopt points.
 var keys = ["a", "b", "c", "d"];
-var has_keys = [];
-var deopt_has = false;
+var property_descriptor_keys = [];
 var deopt_enum = false;
+var deopt_property_descriptor = false;
 
 var handler = {
   ownKeys() {
     if (deopt_enum) {
       %DeoptimizeFunction(f2);
       deopt_enum = false;
     }
     return keys;
   },
-  getOwnPropertyDescriptor() { return { enumerable: true, configurable: true }},
-
-  has(target, k) {
-    if (deopt_has) {
+  getOwnPropertyDescriptor(target, k) {
+    if (deopt_property_descriptor) {
       %DeoptimizeFunction(f2);
-      deopt_has = false;
+      deopt_property_descriptor = false;
     }
-    has_keys.push(k);
-    return true;
-  }
+    property_descriptor_keys.push(k);
+    return { enumerable: true, configurable: true }
+  },
 };
 
 
 var proxy = new Proxy({}, handler);
 var o = {__proto__: proxy};
 
 function f2(o) {
   var result = [];
   for (var i in o) {
     result.push(i);
   }
   return result;
 }
 
 function check_f2() {
   assertEquals(keys, f2(o));
-  assertEquals(keys, has_keys);
-  has_keys.length = 0;
+  assertEquals(keys, property_descriptor_keys);
+  property_descriptor_keys.length = 0;
 }
 
 check_f2();
 check_f2();
 
 // Test lazy deopt after ForInEnumerate
 %OptimizeFunctionOnNextCall(f2);
 deopt_enum = true;
 check_f2();
 
 // Test lazy deopt after FILTER_KEY
 %OptimizeFunctionOnNextCall(f2);
-deopt_has = true;
+deopt_property_descriptor = true;
 check_f2();
 
+
 function f3(o) {
   for (var i in o) {
   }
 }
 
 f3({__proto__:{x:1}});
 f3({__proto__:{x:1}});
 
 %OptimizeFunctionOnNextCall(f3);
 f3(undefined);
 f3(null);
 
 // Reliable repro for an issue previously flushed out by GC stress.
-var handler2 = {

[Jakob Kummerow, 2016/03/18 14:12:00]

That's weird. This careful setup of handler2/proxy2/o2 looks a lot like they
should be used somewhere. Maybe in the f4(o, p) call in line 114? But then the
expectations in check_f4 wouldn't make sense. Hmmm... Fine, drop it.

[Camillo Bruni, 2016/03/18 17:46:34]

yeah, this confused me more that it should have... 

-  getPropertyDescriptor(target, k) {
-    has_keys.push(k);
-    return {value: 10, configurable: true, writable: false, enumerable: true};
-  }
-}
-var proxy2 = new Proxy({}, handler2);
-var o2 = {__proto__: proxy2};
 var p = {x: "x"}
 
 function f4(o, p) {
   var result = [];
   for (var i in o) {
     var j = p.x + "str";
     result.push(i);
   }
   return result;
 }
 
 function check_f4() {
   assertEquals(keys, f4(o, p));
-  assertEquals(keys, has_keys);
-  has_keys.length = 0;
+  assertEquals(keys, property_descriptor_keys);
+  property_descriptor_keys.length = 0;
 }
 
 check_f4();
 check_f4();
 
 %OptimizeFunctionOnNextCall(f4);
 
 p.y = "y";  // Change map, cause eager deopt.
 check_f4();
 
 // Repro for Turbofan equivalent.
 var x;
 var count = 0;
 
 var Debug = debug.Debug;
 
 function listener(event, exec_state, event_data, data) {
   if (event == Debug.DebugEvent.Break) {
     %DeoptimizeFunction(f5);
   }
 }
 
 var handler3 = {
   ownKeys() { return ["a", "b"] },
-  getOwnPropertyDescriptor() { return { enumerable: true, configurable: true }},
-
-  has(target, k) {
+  getOwnPropertyDescriptor(target, k) {
     if (k == "a") count++;
-    if (x) %ScheduleBreak();
-    return true;
+    if (x) %ScheduleBreak()

[Jakob Kummerow, 2016/03/18 14:12:00]

nit: why drop the semicolons?

[Camillo Bruni, 2016/03/18 17:46:34]

random... will re-add ;)

+    return { enumerable: true, configurable: true }
   }
 };
 
 var proxy3 = new Proxy({}, handler3);
 var o3 = {__proto__: proxy3};
 
 function f5() {
   for (var p in o3) {
     print(p);
   }
 }
 
 x = false;
 
 f5(); f5(); f5();
 %OptimizeFunctionOnNextCall(f5);
 x = true;
 count = 0;
 Debug.setListener(listener);
 f5();
 Debug.setListener(null);
 assertEquals(1, count);