Stop using private properties for data properties of cross-origin properties

Since Blink properly supports the incumbent realm now, there is no more need to use OriginSafeMethodSetter, which sets value via V8PrivateProperty.
So there is no need to use V8PrivateProperty also in OriginSafeMethodGetter.

This CL makes it possible to handle "data properties" of cross-origin properties as the proper data properties.

Bug: 715418
Change-Id: I336a8459b80bc63d08a248f3ed7a34dc0806e5ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1844520
Commit-Queue: Marina Sakai <[email protected]>
Reviewed-by: Yuki Shiino <[email protected]>
Reviewed-by: Hitoshi Yoshida <[email protected]>
Cr-Commit-Position: refs/heads/master@{#706304}

Author: Marina Sakai

html/browsers/origin/cross-origin-objects/cross-origin-objects.html

@@ -148,6 +148,9 @@
   assert_throws("SecurityError", function() { win.location.pathname; }, "location.pathname throws cross-origin");
   assert_equals(B.frames, 'override', "Overrides visible in the same-origin case");
   assert_equals(win.frames, win, "Overrides invisible in the cross-origin case");
+  assert_equals(B.focus, 'override', "Overrides visible in the same-origin case");
+  checkFunction(win.focus, Function.prototype);
+  assert_not_equals(win.focus, focus, "Overrides invisible in the cross-origin case");
 }, "Basic sanity-checking");
 
 /*

html/browsers/origin/cross-origin-objects/frame.html

@@ -6,9 +6,10 @@
     document.domain = document.domain;
   }
 
-  // Override the |frames| property to test that such overrides are
+  // Override the |frames| and |focus| property to test that such overrides are
   // properly ignored cross-origin.
   window.frames = "override";
+  window.focus = "override";
 
   // Also add a |then| property to test that it doesn't get exposed.
   window.then = "something";