Adding `@optionalTypeArgs`.

With the new dev build we've got the updated linter and so can use the `@optionalTypeArgs` annotation (in `meta 0.12.0`).

Bonus: this lets us clean up one more Regexp in the `analyze` command! :)

Add a basic scrolling test for the Gallery home page.

Repaint child view on attach / detach.

* run pub for analyze and test

* don't run pub when doing repo analysis

* move logic for when to run pub into the commands

* re-write ternary expression

* Improvements to the Grid list demo

* More nits and fixes to grid demo in gallery

Current numbers from my Nexus 5:
  "average_frame_build_time_millis": 22.6854,
  "missed_frame_build_budget_count": 15,
  "frame_count": 15

Filed https://github.com/flutter/flutter/issues/3296

@yjbanov @hansmuller @vlidholt

Bump dart SDK to 1.16.0-dev.5.0.

...by adding tests to our examples that don't import flutter_test, which
pins the relevant dependencies.

Also, provide more information when complaining about leaked transient
callbacks in tests.

Also, make tests display full information when they have an exception,
by bypassing the throttling we have for Android logging in tests.

Also, make the word wrapping not wrap stack traces if they happen to
be included in exception output.

Also, fix a leaked transient callback in the checkbox code.

Among other things, grabs support for `@optionalTypeArgs`.

This is the last dev push for 1.16.  Here on out we're in cherry-pick season until 1.16 final.

Move flutter drive to use 8183 to not conflict with diagnostic server

When @jason-simons added the diagnostic server on Android this
happened to conflict with flutter drive's usage of 8182.

We really should fix both of these port users to be dynamic
but this fixes https://github.com/flutter/flutter/issues/3291
for now.

@yjbanov

* Fix Block intrinsic functions

* Update block_test.dart

Fix the test per travis

This also shrinks the width of the error messages a bit because now that
we use 'package:' URLs the stacks are a bit narrower.

See https://github.com/flutter/flutter/issues/3233

* styles updates for the api docs

* update library docs

* use the new --favion and --use-categories options for dartdoc

Also fill in some related dartdocs.

Now past halfway though material.dart by files.

Roll engine to c3504b519fcd95179ea832460758712ecd0e433d

This picks up a change which fixes deps files generated by the snapshotter.

* ClampOverscrolls Inherited Widget

* add a --deploy flag to build apk

* update command description

* use an enum instead of a bool param for build variants

* rename buildForDeploy flag to buildVariant

* review comments

Migrate `enable-strict-call-checks` flag to options file.

As per https://github.com/dart-lang/sdk/issues/25723, moves last command-line flag to `.analysis_options`.

Analyze Command lint cleanup.

The push to dev-4 allows us to cleanup a few more bits:
  * `api_docs` lint message special casing (lint fixed)
  * `allowedIdentifiersPattern` (lint fixed)

* more terse flutter upgrade

* fix an issue when updating and the engine update code has changed

* call flutter precache; add a --no-color hidden option

* fix a lint related to getters/setters