Auto merge of #21912 - servo:lighter-bootstrap, r=jdm

Add `--build` and `--emulator-x86` to `./mach bootstrap-android`

This allows not downloading dependencies that are not needed for a particular task.

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etc/ci/bootstrap-android-and-accept-licences.sh

@@ -1,17 +0,0 @@
-#!/usr/bin/env bash
-
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-set -o errexit
-set -o nounset
-set -o pipefail
-
-# We enable pipefail above to satisfy servo-tidy, but disable it again here.
-# In the case of the 'yes' program,
-# exiting when the stdout pipe is broken is expected.
-set +o pipefail
-
-cd $(dirname ${0})/../..
-yes | ./mach bootstrap-android

etc/ci/buildbot_steps.yml

@@ -180,7 +180,7 @@ android:
   - ./mach clean-nightlies --keep 3 --force
   - ./mach clean-cargo-cache --keep 3 --force
   - ./etc/ci/clean_build_artifacts.sh
-  - ./etc/ci/bootstrap-android-and-accept-licences.sh
+  - ./mach bootstrap-android --accept-all-licences --build
   - env --unset ANDROID_NDK --unset ANDROID_SDK ./mach build --android --dev
   - env --unset ANDROID_NDK --unset ANDROID_SDK ./mach package --android --dev
   - bash ./etc/ci/lockfile_changed.sh
@@ -191,7 +191,7 @@ android-mac:
  commands:
   - ./mach clean-nightlies --keep 3 --force
   - ./mach clean-cargo-cache --keep 3 --force
-  - ./etc/ci/bootstrap-android-and-accept-licences.sh
+  - ./mach bootstrap-android --accept-all-licences --build
   - ./mach build --android --dev
   - ./mach package --android --dev
   - bash ./etc/ci/lockfile_changed.sh
@@ -205,7 +205,7 @@ android-x86:
   - ./mach clean-nightlies --keep 3 --force
   - ./mach clean-cargo-cache --keep 3 --force
   - ./etc/ci/clean_build_artifacts.sh
-  - ./etc/ci/bootstrap-android-and-accept-licences.sh
+  - ./mach bootstrap-android --accept-all-licences --build --emulator-x86
   - env --unset ANDROID_NDK --unset ANDROID_SDK ./mach build --target i686-linux-android --release
   - env --unset ANDROID_NDK --unset ANDROID_SDK ./mach test-android-startup --release
   - env --unset ANDROID_NDK --unset ANDROID_SDK ./mach test-wpt-android --release /_mozilla/mozilla/DOMParser.html /_mozilla/mozilla/webgl/context_creation_error.html
@@ -220,7 +220,7 @@ android-nightly:
   - ./mach clean-nightlies --keep 3 --force
   - ./mach clean-cargo-cache --keep 3 --force
   - ./etc/ci/clean_build_artifacts.sh
-  - ./etc/ci/bootstrap-android-and-accept-licences.sh
+  - ./mach bootstrap-android --accept-all-licences --build
   - env --unset ANDROID_NDK --unset ANDROID_SDK ./mach build --android --release
   - env --unset ANDROID_NDK --unset ANDROID_SDK ./mach package --android --release --maven
   - env --unset ANDROID_NDK --unset ANDROID_SDK ./mach build --target=i686-linux-android --release

etc/taskcluster/decision_task.py

@@ -87,7 +87,7 @@ def android_arm32():
         # wget: servo-media-gstreamer’s build script
         .with_script("""
             apt-get install -y --no-install-recommends openjdk-8-jdk-headless file wget
-            ./etc/ci/bootstrap-android-and-accept-licences.sh
+            ./mach bootstrap-android --accept-all-licences --build
             ./mach build --android --release
         """)
         .with_artifacts(