community/firefox-esr: fix FTBFS

error: casts cannot be followed by a field access
   --> servo/components/style/stylesheets/viewport_rule.rs:314:39
    |
314 |                     declaration!($min(value: shorthand.0, important: important)),
    |                                       ^^^^^^^^^^^^^^^^
...
323 |             "width" => ok!(shorthand -> [MinWidth, MaxWidth]),
    |                        -------------------------------------- in this macro invocation
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
7 jobs for !7184 with community/firefox-esr in 2 minutes and 43 seconds
detached
Status Job ID Name Coverage
  Lint
passed #101137
docker-alpine x86_64
lint

00:00:23

 
  Build
failed #101142
docker-alpine ci-build aarch64
build-aarch64

00:00:07

failed #101143
docker-alpine ci-build armv7
build-armv7

00:02:17

failed #101141
docker-alpine ci-build ppc64le
build-ppc64le

00:00:11

failed #101140
docker-alpine ci-build s390x
build-s390x

00:00:06

failed #101139
docker-alpine ci-build x86
build-x86

00:00:08

failed #101138
docker-alpine ci-build x86_64
build-x86_64

00:00:08

 
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