Marked FindLinkImageAtPointForRelativeUrl as flaky.

Bug: 817385
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: Ia4d71b62e3d6fa5dc1e7f5ae8a918c5a1af2c2cd
Reviewed-on: https://chromium-review.googlesource.com/941405
Commit-Queue: Mike Dougherty <michaeldo@chromium.org>
Reviewed-by: Mike Dougherty <michaeldo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539860}

ios/web/web_state/js/context_menu_js_unittest.mm

@@ -604,8 +604,16 @@ TEST_F(ContextMenuJsFindElementAtPointTest,
 
 // Tests that an image link returns details for both the image and the link
 // destination when the image source is a relative url.
+// TODO(crbug.com/817385): This test is flaky on devices.
+#if TARGET_IPHONE_SIMULATOR
+#define MAYBE_FindLinkImageAtPointForRelativeUrl \
+  FindLinkImageAtPointForRelativeUrl
+#else
+#define MAYBE_FindLinkImageAtPointForRelativeUrl \
+  FLAKY_FindLinkImageAtPointForRelativeUrl
+#endif
 TEST_F(ContextMenuJsFindElementAtPointTest,
-       FindLinkImageAtPointForRelativeUrl) {
+       MAYBE_FindLinkImageAtPointForRelativeUrl) {
   NSString* kLinkDest = @"http://destination/";
   NSString* kImageHtml =
       @"<a href='%@'><img width=400 height=400 src='foo'></img></a>";