Bug 1526627 [wpt PR 15256] - [html] Restore coverage for query encodi…

…ng, a=testonly

Automatic update from web-platform-tests
HTML: restore coverage for query encoding

When the query encoding navigation tests were refactored to use WPT's
"variant" feature [1], the new structure omitted one of the encodings
which was previously tested. Although the encoding will be used when a
variant is not specified, the automation tooling only uses variants
which are explicitly specified. This can be observed through the
`--list-tests` flag of the `wpt run` command:

    $ ./wpt run --list-tests firefox html/infrastructure/urls/resolving-urls/query-encoding/navigation.sub.html
    /html/infrastructure/urls/resolving-urls/query-encoding/navigation.sub.html?encoding=utf8
    /html/infrastructure/urls/resolving-urls/query-encoding/navigation.sub.html?encoding=x-cp1251

Explicitly declare the default variant, restoring the original test
coverage.

[1] web-platform-tests/wpt#11300
--

wpt-commits: 0b594535b4d94217964a40288e3f535c452bb8f3
wpt-pr: 15256

UltraBlame original commit: 53e0aa99149f34d0facaa1571ff088c36d1714c7

testing/web-platform/tests/html/infrastructure/urls/resolving-urls/query-encoding/attributes.sub.html

@@ -27,6 +27,22 @@
 ?
 encoding
 =
+windows
+-
+1252
+"
+>
+<
+meta
+name
+=
+variant
+content
+=
+"
+?
+encoding
+=
 x
 -
 cp1251

testing/web-platform/tests/html/infrastructure/urls/resolving-urls/query-encoding/location.sub.html

@@ -27,6 +27,22 @@
 ?
 encoding
 =
+windows
+-
+1252
+"
+>
+<
+meta
+name
+=
+variant
+content
+=
+"
+?
+encoding
+=
 x
 -
 cp1251

testing/web-platform/tests/html/infrastructure/urls/resolving-urls/query-encoding/navigation.sub.html

@@ -27,6 +27,22 @@
 ?
 encoding
 =
+windows
+-
+1252
+"
+>
+<
+meta
+name
+=
+variant
+content
+=
+"
+?
+encoding
+=
 x
 -
 cp1251