This reverts commit 445505d6.

This relands flutter/flutter#33163 with a fix to the integration_ui test.

* Clean up some flutter_tools tests

* Remove arbitrary retry that happens even for fundamental errors, and generally clean up _DevFSHttpWriter.

* Update dependencies (requires fixes; see next commit)

* Fixes for new dependencies.

* Use source list from the compiler to track invalidated files.

* Revert accidental change

* Fix first-time-seen-the-file logic

* Fix/simplify invalidate logic now that we can rely on compiler to let us know what is the cut-off point for invalidation.

* Update devfs mock to accommodate for new fields

* Fix deleted files case

* Analyzer found missing final

* Manual engine roll for 2019-03-19
* Applying patch for Dart SDK changes (see PR #29004)

* fix some formatting issues

* address review comments

* fix indent

* add trailing commas on list/map/parameters

* add trailing commas on Invocation with nb of arg>1

* add commas for widget containing widgets

* add trailing commas if instantiation contains trailing comma

* revert bad change

* Collect devfs stats for better analytics

* Fix fields initialization

* Fix lints

Ensure that cached dill files for builds with --track-widget-creation
always have .track. in the file name to avoid mixing transformed and
untransformed kernel files.

Fixes #22451

* Don't sync first full kernel file.

* Update the comment

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests

Dart 1 is no longer supported in Flutter. Hot reload now always occurs
via kernel file updates (plus any asset bundle changes).

This patch eliminates the --preview-dart-2/--no-preview-dart-2 flag,
hardcoding all uses to true. It also defaults all previewDart2 method
parameters to true, where they hadn't yet been.

A series of subsequent patches will eliminate all previewDart2
parameters and the associated code from within the codebase.

DevFS.update only runs in Dart 2 mode when the generator parameter is
supplied. In Dart 2 mode, both mainPath and pathToReload are required
parameters; this patch marks them as such.

generator is required for running in Dart 2. All call sites other than tests already explicitly set this value.

Note the statements on line 510 and line 516 for why mainPath and pathToReload are required.

* Remove uses of deprecated constants
* Change int.parse to int.tryParse where appropriate

* Preserve original kernel file for isolate spawn requests.

This change gives incremental kernel files ".incremental.dill" extension thereby preserving original kernel file.

Bug: https://github.com/flutter/flutter/issues/16084
Bug: https://github.com/flutter/flutter/issues/17012
Bug: https://github.com/flutter/flutter/issues/17983

* Factor out naming logic into separate function

* Fix string vs uri

fuchsia_tester.dart still assumes Dart 1. Previously, it ran tests directly
from source, flutter_platform.dart automatically runs a kernel compile when
operating in Dart 2 mode, but this assumes a functional Dart SDK is available
in the artifacts directly, and fuchsia_tester.dart mocks out the artifacts
directory with an empty temp dir.

Remaining work is:
1. Get the frontend server building as a dependency on Fuchsia.
2. Patch fuchsia_tester.dart to use a valid Dart SDK and frontend server.

This also reverts migration to Dart 2 typedef syntax.

This reverts commit 6c56bb24. (#18362)
This reverts commit 3daebd05. (#18316)

* It's time to #deleteDart1 (#18293)

Eliminates support for Dart 1 in flutter_tools, and drops our Dart 1
benchmarks. All commands now run in Dart 1 mode only.

Eliminates --preview-dart-2 / --no-preview-dart-2 support.

* Fix indentation, remove no longer necessary .toList()

* Only push udpated kernel if >0 invalidated srcs