When attempting to locate an element in the Flutter Gallery transition
performance driver test, attempt to scroll downward in increments of 25%
of the screen rather than by an absolute pixel amount.

This helps get the test passing on devices with relatively small screen
heights.

* Add a draggable axis restrictor and tests

1. Make CupertinoSwitch use BoxShadow.toPaint() so that it respects
   the `debugDisableShadows` flag.
2. Increase blue radius on debug banner
3. Only stroke "synthetic shadow" borders if elevation is positive.

In theory, this should aid with tree shaking and minutely optimize the code in release builds.

Before this change, if CDPATH was set, and you type (from the flutter root) "bin/flutter --version" you would get an error.

This is because the cd command in follow_links was printing the directory Bash chose from the CDPATH to stdout, causing the path to have a newline in it, which understandably confuses the rest of the script.

Take into account the subtitle height when adjusting the height of the widget. Added a test.

* Search for a suitable ARM sysroot instead of hardcoding it;
* Add facility to explain why NDK was not found;

This contains the following commits:

flutter/engine@9ae10ef Revert f6359e4111d37652409e2392fdb3cb72f1119c2a

This contains the following commits:

flutter/engine@b856303 Revert 37e20af6a324cd4cfa1324b8c644712ef8224359
flutter/engine@39c02c4 Fixed Windows build after Blink removal
flutter/engine@4a4cff9 Remove Blink code
flutter/engine@f2acd0a Roll src/third_party/skia/ f31fece65..1d686a962 (10 commits)

Adds unit tests for the following AOT build configurations:
* iOS armv7 profile
* iOS armv7 release
* Android armv7 profile (AOT blob)
* Android arm64 profile (AOT blob)
* Android armv7 release (AOT blob)
* Android arm64 release (AOT blob)

Further digging revealed that the reason --no-sim-use-hardfp was
required to be specified explicitly was that Android engine gen_snapshot
binaries are built on Windows with target_os=win.

This fixes #17169 by adding onChangeStart and onChangeEnd to the slider. These will be called when the user starts a change, and when they end a change, regardless of whether that change is a tap or a drag.

These differ from onChanged, in that they only report when the user starts and ends an interaction, not at every slight change.

The non-deprecated variants aren't widely available yet

Previously, the only hook into the rasterizer schreenshot code path
was via FlutterDriver.screenshot.  This adds the ability for the
Flutter tool to hook into all three types of screenshots:

1. device (e.g. `adb shell screencap`)
2. Skia (capture spk)
3. Rasterizer (capture PNG via the engine)

This contains the following commits:

flutter/engine@fade83c Bypass the raster cache when screenshotting

Before this change, if you specified a non-null textTheme, but the theme you specified didn't have a body2 defined, then creating a ChipTheme would assert (which means creating a ThemeData would fail).

This adds handling for this corner case to default to reasonable values in that case. The slider had the same problem, but for accentTextTheme, so I fixed that too.

While I had the patient open, Hans and I noticed that TextTheme.merge wasn't doing the right thing in the case where some members were null either, so I fixed that, and added some examples, since merge/copyWith are common operations that are not always well understood.

Fixes #17251

* no longer use the analyzer version shipped in the sdk

* update all package versions to the latest

This reverts #17147, which was safe under the assumption that
getArtifactPath() returns a platform-specific gen_snapshot instance
(which have the correct default set for this flag) -- it turns out that
though we pass the platform to getArtifactPath(), we always return the
host gen_snapshot for Android.

A followup patch will update getArtifactPath and revert this patch.

re-write flutter analyze (the single-shot and --flutter-repo) to use the analysis server