This also involves switching from Core JIT to App JIT snapshot, and replacing per-isolate VM snapshot with the shared VM snapshot.

For now there is no separate update bundle file, as the generated update gets packaged directly into the APK for testing purposes.

This changes the compiler output for gradle to be less verbose and more easily read.

This only applies to compilation error messages: other gradle messages will continue to print as before.

It also fixes a small problem with the performance measurement printing (see that "7.1s" on it's own line in the original?) so that if something is expected to have multiple lines of output, it prints an initial line, and a "Done" line with the elapsed time, so that it's possible to know what the time applies to.

It also updates the spinner to be fancier, at least on platforms other than Windows (which is missing a lot of symbols in its console font).

Addresses #17307

This tickled a bug in KernelCompiler.compile() where the fingerprinter
doesn't include the outputFilePath in its list of dependencies. As such,
if the output .dill file is missing or corrupted, the fingerprint still
matches and re-compile is skipped, even though it shouldn't be. I'll fix
that in a followup, then look at how this triggered that issue. My
hypothesis is that that it's due to the aot kernel compile and bundle
kernel compile have separate output directories for the .dill files
(build/ vs build/aot) but the same output directory for the associated
depfiles (due to this patch).

This reverts commit 43a106e9.

The --snapshot argument was only necessary in Dart 1. The --depfile
argument was only used in Dart 2 mode to pass to the kernel compiler,
but was inconsistent with the 'build aot' command, where the depfile was
always set to build/kernel_compile.d.

This patch updates 'build bundle' to emit the depfile to a location
consistent with the 'build aot' command; since it's not intended to be
user-configurable and flutter.gradle hardcodes the location to
build/kernel_compile.d either way, this patch also eliminates the
ability to configure the filename altogether.

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.

* Revert "iOS Dialog blur, brightness, and layout (#18381)"

This reverts commit 21bc9f1b.

* Revert "Flutter tool support for dynamic code. (#20543)"

This reverts commit 25ba90aa.

Add flutter tool support for creating app-specific VM snapshots.

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

Several benchmarks started failing during kernel compile:
1. Timeouts:
   * commands_test
   * hot_mode_dev_cycle__benchmark
   * run_machine_concurrent_hot_reload
   * service_extensions_test

2. Kernel compiler crash:
   * hot_mode_dev_cycle_linux__benchmark
   * routing_test

3. Unexpected termination:
   * hot_mode_dev_cycle_win__benchmark

This reverts commit ed63e708.

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.

The change in 8b8d368d has only renamed the flag in a subset of the
places.

This reverts commit 59bb2dba.

This reverts commit 0f557e72.

This reverts commit dac1baf4.

This updates the Android build to declare the kernel compile depfile as
an output and its contents as inputs when running with --preview-dart-2
(the default mode).

The 'flutter build aot' command behaves differently depending on whether
it's running in Dart 1 or Dart 2 mode:

* Dart 1: the entrypoint Dart file (typically main.dart) is passed
  directly to gen_snapshot, which then emits snapshot.d, whose contents
  list the transitive closure of Dart dependencies (input files) for the
  snapshot. snapshot.d is a declared output, its contents (plus
  gen_snapshot itself) constitute the set of input files to the Gradle
  build action.

* Dart 2: then entrypoint Dart file (typically main.dart) is first
  compiled with the Dart kernel frontend. This emits kernel_compile.d,
  whose contents list the transitive closure of Dart dependencies (input
  files) for the kernel 'dill' output file. This 'dill' file is then
  passed to gen_snapshot, which emits snapshot.d, whose contents are
  empty. As of this change, both snapshot.d and kernel_compile.d are
  declared outputs, and their contents (plus gen_snapshot and the
  frontend compiler themselves) constitute the set of input files to the
  Gradle build action.

This fixes a bug wherein profile/release AOT outputs were not
invalidated due to snapshot.d being empty, and kernel_compile.d being
ignored. This was introduced during recent refactoring of the AOT build
code, wherein the kernel compile and gen_snapshot actions were changed
to emit independent depfiles (previously one stomped -- or failed to --
on the other's output).

* Revert "Revert "Reland pass filesystem options (#15622)" (#15651)"

This reverts commit 0f3eada0.

* Fix for windows failing test

* !isEmpty -> isNotEmpty

This reverts commit bbcf55a5 as it breaks hot reload on Windows.

* Revert "Revert "Pass filesystem-root, filesystem-scheme options through `flutter run, build` and gradle. (#15592)" (#15621)"

This reverts commit c663e336.

* Check whether filesystem-root is emtpy.

* Restore broken merge

* Fix windows test

* Adjust regex in test. Invalidate files by file path.

Revert "Pass filesystem-root, filesystem-scheme options through `flutter run, build` and gradle. (#15592)" (#15621)

This reverts commit 0f659fb1 as it
breaks bin/tasks/gradle_plugin_test.dart.

* Pass filesystem-root, filesystem-scheme options through flutter run/build/gradle.

Pass extra front-end and gen_snapshot options to GenerateDependencies gradle task, as it also runs 'flutter build aot' (#14980)

* Use depfile in --preview-dart-2 mode.

* Generate and use frontend_server.d to guard against reusing outdated dill files when frontend_server changes.