...and break the navigator<->routes circular dependency.

This is a step towards fixing https://github.com/flutter/flutter/issues/9577 but doesn't yet do so.

Fixes #11327

This reverts commit 4b4cabb7.

* fire service protocol extension events for frames

* start time in micros

* introduce a profile() function; only send frame events when in profile (or debug) modes

* moved the profile() function to foundation/profile.dart

* refactor to make the change more testable; test the change

* fire service protocol events by listening to onFrameInfo

* remove the frame event stream; add a devicelab test

* remove a todo

* final

The output location of gen_snapshot differs based on the engine's target
platform, and we don't know the target platform when building a
platform-independent FLX in JIT mode.

It was 8.0. It's now arbitrarily 18.0.

Changing this required adjusting some tests. Adjusting the tests
required debugging the tests. Debugging the tests required some tools
to help debugging gesture recognizers and gesture arenas, so I added
some. It also required updating some toString() methods which resulted
in some changes to the tree diagnostics logic.

Also I cleaned up some docs while I was at it.

* remove the flutter view cache; fix the ability to quit the app after a full restart

* improve test

* update test

Refactor RenderObject.toStringDeep and Widget.toStringDeep code to use DiagnosticsNode.

This reverts commit bc4a3f17.

* Support automaticallyImplyLeading param in AppBar

* Review fixes

* fix review comments

* ignore postpauseevents when reloading

* Update run_hot.dart

comment changes to kick the appveyor bot

Fixes https://github.com/flutter/flutter/issues/11323

Mainly, this adds documentation to members that were previously
lacking documentation.

It also adds a big block of documentation about improving performance
of widgets.

This also removes some references to package:collection and adds
global setEquals and listEquals methods in foundation that we can use.
(setEquals in particular should be much faster than the
package:collection equivalent, though both should be faster as they
avoid allocating new objects.) All remaining references now qualify
the import so we know what our remaining dependencies are.

Also lots of code reordering in Flutter driver to make the code
consistent and apply the style guide more thoroughly.

* Fix physics with NestedScrollView

* Review feedback

* Optimise AnimatedSize for the tight case.
* Remove `default` from a switch statement over enum (so that analyzer will complain if we add enum values).
* Adopt the Size since we use it after the child may have changed (which would throw normally).
* AnimatedCrossFade.layoutBuilder

* Flutter create widget test template.

Running `flutter create —with-widget-test` produces a test/widget_test.dart sample widget test.

* Generate widget test bits in flutter create.

* Path fix.

* Added types.

* Skip shell testing on windows.

* formatting fixes

* Update test sample to test the sample app.

* Formatting tweak.

* Prefix and Suffix support for TextFields

* Adding Tests

* Removing spurious newline.

* Fixing a small problem with the test

* Code review changes

* Code Review Changes

* Review Changes

* Export the new StrokeJoin enum

* Added example for line styles, and enabled line join styles.

* Reverting inadvertent change to main.dart.

* Updated due to code review of engine code

* Removed example.

* Added arguments to named routes, with test.

* Fixing some formatting

* Fixing Navigator.pop for named routes.

* Fixing comment.

* Simplifying test.

* Fixing new -> const for Text object.

* Tiny text change (also to kick a new Travis build)

* Added a more realistic test case.

* Reverting unintentional iml changes.

* Fixing trailing newline

* Removing some changes that snuck in.

Extract common text selection overlay logic from Material to Widget and create a Cupertino version of the overlays

This is similar to an optimization done in PhysicalModelLayer::Paint in the engine

This reverts commit e13e7806.

Turns out that with this patch, we aren't actually catching all
errors. For example, `flutter analyze --flutter-repo --watch` didn't
report errors in `dev/devicelab/test/adb_test.dart`.

* fix sample code

* review comments

* review comments

* document other members for extra bonus points

* adds inactiveColor and showThumb to Slider

* add customizable color and showThumb tests

* remove showThumb, add negative tests

Fixes https://github.com/flutter/flutter/issues/11314

Create one listener that merges the leading and trailing glow controllers and use it in each paint (#11311)

If a new listener is created for each paint, then the leading and trailing
controllers will accumulate and invoke a list of all those listeners

Changes introduced in
https://github.com/flutter/engine/commit/8ba522eeae35d8c70ada3c7b8e200ca2274f4f95
has removed from the `_flutter.listViews` the thread synchronization
side effect used during benchmarks.

The thread synchronization is restored via the new
`_flutter.flushUIThreadTasks` RPC.

Fixes https://github.com/flutter/flutter/issues/11241

Related https://github.com/flutter/engine/pull/3898

Required for https://github.com/flutter/flutter/pull/11282