Rename all the "2" classes related to scrolling to remove the "2". Now that the
old scrolling code is gone, we don't need to use the suffix.

* Do not attempt to merge non-fat frameworks in Xcode build

During the Xcode build, we strip code irrelevant to the target
architecture in frameworks used by the application. In the case of
non-fat executables, no stripping occurs, so the frameworks can be used
as-is. No merge & replace step is necessary.

* fixup! Do not attempt to merge non-fat frameworks in Xcode build

* More better toStrings and more vigorous smoke testing of gallery

* Update scroll_controller.dart

* Update sliver.dart

* Add --start-paused doc

* correcting > Observatory

* Updating --start-paused option w/feedback

Artifacts are now located in a central place.
This will enable us to downlaod artifacts when we need them (instead of
downloading them all upfront).
This also makes replacing sky_snapshot with gen_snapshot easier.

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.