browser(webkit): respect download attribute (#5474)

References #5396

browser_patches/webkit/BUILD_NUMBER

@@ -1,2 +1,2 @@
-1434
-Changed: yurys@chromium.org Mon 08 Feb 2021 09:49:33 AM PST
+1435
+Changed: lushnikov@chromium.org Tue Feb 16 10:30:00 MST 2021

browser_patches/webkit/embedder/Playwright/mac/BrowserWindowController.m

@@ -670,6 +670,11 @@ static NSSet *dataTypes()
 {
     LOG(@"decidePolicyForNavigationAction");
 
+    if (navigationAction.shouldPerformDownload) {
+        decisionHandler(WKNavigationActionPolicyDownload);
+        return;
+    }
+
     if (navigationAction._canHandleRequest) {
         decisionHandler(WKNavigationActionPolicyAllow);
         return;