Rename a flag in layout test update_hover_after_layout_change.html

When I merged and rename the flags to update hover for layout change
and scroll, I did not change the flag in Rename a flag in layout test
update_hover_after_layout_change.html, it should be
updateHoverAtBeginFrame.


Bug: 877132
Change-Id: I2032283cc4bb36a17c0e805dacc35367ee630877
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1738668Reviewed-by: Navid Zolghadr <nzolghadr@chromium.org>
Commit-Queue: Lan Wei <lanwei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#684471}

third_party/blink/web_tests/fast/events/update_hover_after_layout_change.html

@@ -18,7 +18,7 @@
 </style>
 
 <script>
-internals.runtimeFlags.updateHoverFromLayoutChangeAtBeginFrameEnabled = true;
+internals.runtimeFlags.updateHoverAtBeginFrameEnabled = true;
 
 var eventList = [];
 var x = 100;