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).

Since RelativeRect's whole purpose in life is to make work with Stack
easier, it's silly that you can't directly use it with Positioned.

Also, tests for RelativeRect.
And fixes for the bugs that found...

Also use the word "dropdown" consistently over "drop down".

... and run some more tests on Windows.