Fix test: drag-files-to-editable-element.html

The tested feature regressed, but no one realized it, because the test continued
to pass.

Instead of displaying the filenames in the <div>, a new navigation to the file
happened. Starting the navigation causes the current Document to stop and the
test to finish early. The tests finished before it has executed any assertions.

This CL fixes the test, but not the regression.

Bug: 821455, 831155
Change-Id: I61b9cca80677ca2caed72b0e9cf6074f73c2ad6a
Reviewed-on: https://chromium-review.googlesource.com/1094879
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#566800}

third_party/WebKit/LayoutTests/TestExpectations

@@ -2037,7 +2037,7 @@ crbug.com/698135 external/wpt/editing/run/delete.html [ Crash Failure Timeout ]
 
 crbug.com/813098 external/wpt/editing/run/removeformat.html [ Timeout Pass ]
 
-crbug.com/821455 [ Linux ] editing/pasteboard/drag-files-to-editable-element.html [ Failure Pass ]
+crbug.com/821455 editing/pasteboard/drag-files-to-editable-element.html [ Failure ]
 
 crbug.com/688613 external/wpt/mediacapture-streams/MediaStreamTrack-MediaElement-disabled-audio-is-silence.https.html [ Skip ]
 crbug.com/688613 virtual/feature-policy-permissions/external/wpt/mediacapture-streams/MediaStreamTrack-MediaElement-disabled-audio-is-silence.https.html [ Skip ]

third_party/WebKit/LayoutTests/editing/pasteboard/drag-files-to-editable-element.html

@@ -11,15 +11,22 @@ description('If we drag files onto an editable area, then the filenames should b
 
 var result;
 
+jsTestIsAsync = true;
 function startTest()
 {
     var editable = document.getElementById("editable");
     if (window.eventSender) {
-        dragFilesOntoEditable(['foo', 'bar', 'baz']);
+        dragFilesOntoEditable([
+          './resources/drag-files-to-editable-element-fail', 
+          './resources/foo',
+          './resources/bar']);
         result = editable.innerHTML.replace(/file.*?LayoutTests/g, "LayoutTests");
-        shouldBeEqualToString('result', '<div>LayoutTests/editing/pasteboard/foo</div><div>LayoutTests/editing/pasteboard/bar</div><div>LayoutTests/editing/pasteboard/baz</div>');
+        shouldBeEqualToString('result',
+          '<div>LayoutTests/editing/pasteboard/resources/drag-files-to-editable-element-fails</div>'+
+          '<div>LayoutTests/editing/pasteboard/resources/foo</div>'+
+          '<div>LayoutTests/editing/pasteboard/resources/bar</div>');
         editable.innerHTML = '';
-        window.stop();
+        finishJSTest();
     }
 }
 

third_party/WebKit/LayoutTests/editing/pasteboard/resources/drag-files-to-editable-element-fail

+If we drag files onto an editable area, then the filenames should be inserted
+into the editable area. That's not what happened. Instead, the browser navigated
+to the first file.
+
+TEST FAILED.