Also: Fix some analyzer warnings.

* Support iOS screenshot 1/3

* Use path.join

* use fs.path instead

Fixes https://github.com/flutter/flutter/issues/5935

* ups pinned `test` to `0.12.15+9` (to play nice w/ the latest analyzer)
* integrates `analyzer` with analysis driver defaulting to ON

Fixes #8209

All the clients have migrated to Scrollable2.

Update stack_trace_test.dart for changes to the naming of async body functions.

This does not attempt to correct any logic, only to port it as written.

The API changed a bit to take into account what is newly available and
no longer available in the new world.

* Enable Gradle Workflow on Windows

With this the app created by `flutter create` now compiles on Windows.

* Move OS check to gradle file

* Move simulator screenshot logic to use simctl

* Add simulator screenshot tests

- ScrollableList
 - ScrollableLazyList
 - LazyBlock
 - MaterialList

Clients should use ListView instead.

Previously, the scroll correction code path was untested. This patch
introduces a test for the code path and fixes two issues with it.
There's likely more work we'll need to do in this area to nail down all
the cases.

Fixes #8155

This assumes a fix to https://github.com/dart-lang/test/issues/542

The timeout added in this patch is a workaround for https://github.com/dart-lang/coverage/issues/165

This reverts commit fac9efba.

The timeout was fixed by 6795c4ab.

Fixes #8200

Fixes #7166

Also cleans up from an aborted attempt at #5793

Replaces unprintable characters with alternative symbols.

If a developer has installed the Xcode command-line tools, then later
installs Xcode, they may need to run xcode-select to update the path of
the command-line tools to that of the new installation.

This reverts commit 8da4778e.

* Update hello_world to new gradle based build flow

* Update flutter_gallery to gradle based build

* Align hello_services with new gradle based build

* Update platform_services to new gradle based build

* Upgrade stock to gradle based build

The "old" APK build did not include Roboto fonts, but the new
Gradle-based build did. This is due to `flutter build flx` defaulting to
include the fonts, where the old `flutter build apk` defaulted to NOT
include them.

So let's change the Gradle build to also not include Roboto fonts.

Fixes #8149

The replacements are ListView and SingleChildScrollView, respectively.

Fixes https://github.com/flutter/flutter/issues/8017

We can't read our size in the offset setter because we might be in the middle
of layout. This issue also occured with the sliver-based viewport.

* Roll engine to b64c88766dbd83bf4bab1cd1cd1757139b6cdb74.

Picks up changes to include inlined frames and line numbers in AOT stack traces.

* Adjust/weaken stack_trace_test.dart to pass in the face of async causal stack traces (Issue #8128).