ExplicitSnapshotsChangeUponNavigation API test often fails

https://bugs.webkit.org/show_bug.cgi?id=172475
<rdar://problem/31688322>

Reviewed by Simon Fraser.

* TestWebKitAPI/cocoa/TestWKWebView.mm:
(-[TestWKWebView _setUpTestWindow:]):
Make TestWKWebView's window layer-backed. This is now the default,
and it's also easy to accidentally write a test that depends on it
(for example, ExplicitSnapshotsChangeUponNavigation adds an NSBox,
which becomes layer backed, just like the WKWebView, but with no
common layer-backed ancestor).


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@217249 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Author: [email protected]

Tools/ChangeLog

@@ -1,3 +1,19 @@
+2017-05-22  Tim Horton  <[email protected]>
+
+        ExplicitSnapshotsChangeUponNavigation API test often fails
+        https://bugs.webkit.org/show_bug.cgi?id=172475
+        <rdar://problem/31688322>
+
+        Reviewed by Simon Fraser.
+
+        * TestWebKitAPI/cocoa/TestWKWebView.mm:
+        (-[TestWKWebView _setUpTestWindow:]):
+        Make TestWKWebView's window layer-backed. This is now the default,
+        and it's also easy to accidentally write a test that depends on it
+        (for example, ExplicitSnapshotsChangeUponNavigation adds an NSBox,
+        which becomes layer backed, just like the WKWebView, but with no
+        common layer-backed ancestor).
+
 2017-05-22  youenn fablet  <[email protected]>
 
         Resync web-platform-tests up to 8df7c9c215678328212f232ce0b5270c505a8563

Tools/TestWebKitAPI/cocoa/TestWKWebView.mm

@@ -191,6 +191,7 @@ - (void)_setUpTestWindow:(NSRect)frame
     _hostWindow = adoptNS([[TestWKWebViewHostWindow alloc] initWithContentRect:frame styleMask:NSWindowStyleMaskBorderless backing:NSBackingStoreBuffered defer:NO]);
     [_hostWindow setFrameOrigin:NSMakePoint(0, 0)];
     [_hostWindow setIsVisible:YES];
+    [_hostWindow contentView].wantsLayer = YES;
     [[_hostWindow contentView] addSubview:self];
     [_hostWindow makeKeyAndOrderFront:self];
 #else