On Win 64-bit builds only, I've encountered the "Brackets fixup depth exceeds size of bracket vector." error

You can see it here:
https://build.chromium.org/p/chromium.win/builders/Win%20x64%20GN%20%28dbg%29/builds/19191/steps/content_browsertests%20on%20Windows-7-SP1/logs/RenderViewImplTest.OnHandleKeyboardEvent

The test that produced this error caught my attention and ended up I deleting it here: https://codereview.chromium.org/1767773002

However, the error itself doesn't look like it should have been happening. To reproduce:

1) Revert https://crrev.com/2c76d1049aed5a8ca9b32459a5633388505fa877 locally
2) Apply https://codereview.chromium.org/1740173003 (if it hasn't landed yet)
2) Run RenderViewImplTest.OnHandleKeyboardEvent on 64-bin Windows build (in debug)