This patch migrates iOS device listing from using Xcode instruments to
using the libimobiledevice tools idevice_id and ideviceinfo.

ideviceinfo was previously incompatible with iOS 11 physical devices;
this has now been fixed.

In 58fe8237 flutter_tools migrated from
libimobiledevice-based device listing on iOS to using Xcode instruments
to work around the lack of support for iOS 11. Using instruments entails
several downsides, including a significantly higher performance hit, and
leaking hung DTServiceHub processes in certain cases when a simulator is
running, necessitating workarounds in which we watched for, and cleaned
up leaked DTServiceHub processes. This patch returns reverts the move to
instruments now that it's no longer necessary.

This reverts commit 58fe8237.

Applies horizontal safe area insets to the Contacts demo in the Gallery.
This is to support the iPhone X sensor housing notch and other similarly
creative display features when in landscape orientation.

We now require Xcode 9.0, which ships with the iOS 11 SDK, for iOS
builds. This change does not affect the minimum supported iOS deployment
target, which remains iOS 8.

The iOS 11 SDK adds support for safe area insets, which model the status
bar, iPhone X home indicator, and symmetric horizontal insets to avoid
the iPhone X sensor housing when in landscape mode.

This re-lands flutter/flutter#13608 now that the devicelab Macs have
been updated to Xcode 9.

No need to update the compositing bits all the time.

Applies any additional bottom, left, and right media padding inside the
snackbar, if present. This accounts for the iPhone X home indicator
widget and horizontal padding for the sensor housing notch in landscape
orientation.

XZ is about 50MB smaller, and it works on both Mac and Linux.

* split doc paragraph

* specify shouldRepaint argument nullability

* review

Applies top, left, right media padding to avoid placing content within
the safe area insets (e.g. iPhone X notch area in landscape
orientation).

This is the first step in a two-step process of moving the package preparation step from a recipe in chrome_infra to a dart script in the flutter repo. This will make it easier to make changes to the process. The second step is to change the infra recipe to call this script.

In addition, I added a step to the packaging process to run flutter create for each type of template so that any pub dependencies of the templates get added to the cache that gets packaged (and thus users can run flutter create --offline and have it work).

Note that the actual packaging into a "tar" or "zip" file now happens here, so a developer could actually run this script on their machine to create a package.

This lets people poke at navigators without having to get their
BuildContext from a build function or State first.

By default BoxScrollView (and hence ListView, which is a subclass)
padding is the media padding along its scroll axis in order to avoid
placing list items within areas where user interaction should be
minimised -- e.g. under the status bar, or in and around the iPhone X
notch in landscape mode.

In cases where a list item should occupy the padding area, developers
should set the ListView padding to EdgeInsets.zero so as not to pick up
the default media padding. For widgets inside the drawer that should
avoid safe areas, developers can add a SafeArea widget.

Our devicelab machines have not yet been upgraded to Xcode 9. Once this
has been done, I'll re-land this.

This reverts commit 0fac5f01.

We now require Xcode 9.0, which ships with the iOS 11 SDK, for iOS
builds. This change does not affect the minimum supported iOS deployment
target, which remains iOS 8.

The iOS 11 SDK adds support for safe area insets, which model the status
bar, iPhone X home indicator, and symmetric horizontal insets to avoid
the iPhone X sensor housing when in landscape mode.

Applies media padding (e.g. iPhone X safe area insets) to the Material Design demos in the Gallery.

Covers the following demos:
* Buttons (via the TabbedComponentDemoScaffold change)
* Cards
* Expansion panels
* Grid list
* Icons
* Images (via the TabbedComponentDemoScaffold change)
* Page Selector
* Progress Indicator
* Scrollable tabs
* Selection controls (via the TabbedComponentDemoScaffold change)
* Snack bar
* Tabs
* Text fields
* Tooltips

Fixes #13594

* make date picker accessible

* make test file lookup location-independent

* address some comments

* always wrap in IgnorePointer

* no bitmasks for flags and actions

* recommend List<*>

Adds safe areas around:
1. The body of the colour swatch view (tab 1)
2. The chat header (tab 2)
3. The chat bubbles (tab 2)
4. The 'Sign In' launcher button (tab 3)

Rather than use a Center widget, center the title using AppBar's
centerTitle property. This ensures the title is horizontally centred
with respect to the screen rather than centred in the space between the
leading and trailing app bar widgets, which are asymmetrical in Shrine.

Applies top, left, right media padding for iOS safe area insets. This is
a follow-up to the media padding applied to large titles in
flutter/flutter#13550.

Fixes https://github.com/flutter/flutter/issues/10695

* flutter update-packages

* update plugin registrant for flutter_gallery

* Update plugin test template.

* Add flutter test run verification.

* Tweak and test runs for package projects.

* Revert "Revert engine (#13547)"

This reverts commit ee65db11.

* Keep flaky mark

This reverts commit 05d6b08f.

* partial

* add doc and warning

* add correction

* review

* fix test