WPT import https://crrev.com/c/1188439 introduced new failures in external/wpt/html/rendering/non-replaced-elements/the-fieldset-element-0:

List of new failures:
[ Linux ] external/wpt/html/rendering/non-replaced-elements/the-fieldset-element-0/legend-align.html new failing tests: https://crrev.com/c/1188439/4/third_party/WebKit/LayoutTests/platform/linux/external/wpt/html/rendering/non-replaced-elements/the-fieldset-element-0/legend-align-expected.txt
[ Mac ] external/wpt/html/rendering/non-replaced-elements/the-fieldset-element-0/legend-align.html new failing tests: https://crrev.com/c/1188439/4/third_party/WebKit/LayoutTests/platform/mac/external/wpt/html/rendering/non-replaced-elements/the-fieldset-element-0/legend-align-expected.txt
[ Win ] external/wpt/html/rendering/non-replaced-elements/the-fieldset-element-0/legend-align.html new failing tests: https://crrev.com/c/1188439/4/third_party/WebKit/LayoutTests/platform/win/external/wpt/html/rendering/non-replaced-elements/the-fieldset-element-0/legend-align-expected.txt

This import contains upstream changes from 267a39b7d4dd76e83131405ab6854bd14e65a27c to 8dd18afacc7a7cf9969592d8dbd74c20e6d6df8e:
HTML: fieldset legend should inherit alignment: https://github.com/web-platform-tests/wpt/commit/8dd18afacc7a7cf9969592d8dbd74c20e6d6df8e [affecting this directory]
[BackgroundFetch] Part 1: Remove BackgroundFetchSettledFetches.: https://github.com/web-platform-tests/wpt/commit/0594f4ef03914ed61a07ef9bfa888633f4d510aa
Merge pull request #5302 from gsnedders/built-selectors: https://github.com/web-platform-tests/wpt/commit/37a321876d38e26023402c677f333d41a4a5d216
HTML: fixup for legend position: relative test: https://github.com/web-platform-tests/wpt/commit/151c82eb83b29973ade57a861ec6f7b7350c5cf3 [affecting this directory]
Assume xml:id isn't supported: https://github.com/web-platform-tests/wpt/commit/592e7dbe335530f83652eb2639444fe523d0cb8a
Per Selectors 4, :not can be an argument of itself: https://github.com/web-platform-tests/wpt/commit/6afafed79c61821bee9d398fa9bd698badf66a7c
Fix lint errors in selectors3 testsuite: https://github.com/web-platform-tests/wpt/commit/f651b87973f3ad9156db73bcbb5b70b9835998ca
Delete unbuilt css3-selectors tests; move built tests up: https://github.com/web-platform-tests/wpt/commit/22e174410e37c306cb10498ece18a6555b0bc690
Add references for a third of the css3-selectors testsuite: https://github.com/web-platform-tests/wpt/commit/4f2493431fb104752c9a4b721b99838e08f9d717
Commit the built selectors3 testsuite: https://github.com/web-platform-tests/wpt/commit/2b4764f2b34f55fd4c410054e4995cb0a2cb6c2b
Include author: https://github.com/web-platform-tests/wpt/commit/4d82b84f7f143c9a033db2ff5a815a505b55e718
Get rid of links between tests: https://github.com/web-platform-tests/wpt/commit/c72fb8396fe74efb0dcf25748d0b8113c5e22a7b
Output namespace attributes in a constant order: https://github.com/web-platform-tests/wpt/commit/1881d71f3557c427cf1df93b2adf1d26fa9731df
Add enough metadata for the CSS build system to cope: https://github.com/web-platform-tests/wpt/commit/17e9340f3101787453eb228b5d155d6e6e060d64
Change css/ .gitignore to only match what it should: https://github.com/web-platform-tests/wpt/commit/a97cd355b6477c9871017417e40e52eb6f8b7c9c
Strip selectors3 build system back to only generate XHTML unadorned tests: https://github.com/web-platform-tests/wpt/commit/258680cc7f41341bfbbd748859392f5e42160fe6
Move all the unbuilt selectors tests into a subdirectory so they can build: https://github.com/web-platform-tests/wpt/commit/c32b960dfc4de300a842b312d49be07fc502743f
[HTTP/2.0][WIP] H2 server documentation (#12655): https://github.com/web-platform-tests/wpt/commit/96508b50374beb53d52373b5f585c05a246cf745
add romandev (#12582): https://github.com/web-platform-tests/wpt/commit/0976ae3d6e1ad9000ee2d3724a3b03dd2d3e7d17
HTML: review followup (#12662): https://github.com/web-platform-tests/wpt/commit/a63935ce4574b32d850cf0063f6ea508ad517986 [affecting this directory]
Fullscreen elements that were root level elements weren't sized properly.: https://github.com/web-platform-tests/wpt/commit/3588ed998f005477df1060cdee0560b9e47c8509
HTML: fix a bug in img environment changes test: https://github.com/web-platform-tests/wpt/commit/d0960dcdfc8e25c3bdbd487787ec61858e0e1937 [affecting this directory]
Revert "Merge pull request #10344 from nox/var-gt-const": https://github.com/web-platform-tests/wpt/commit/1d7a97518ff59e331f7871b11c2ecbba725e8445