* work in progress

* work in progress

Move generated entry points JSON out of flutter_patched_sdk, add an option to pass entry points to frontend_server (#4734)

Flutter downloads only one version of flutter_patched_sdk, which was obtained from host_debug build on Linux. Generated entry points JSON files are different in profile and release builds (as release build omits observatory), so these files should be downloaded independently of flutter_patched_sdk.

This PR moves generated entry points JSON files from flutter_patched_sdk to a separate directory (out/*/dart_entry_points) and adds an option to specify entry points to frontend_server (as Flutter tools will need to pass custom locations of entry points files outside of flutter_patched_sdk).

NSLocale objectForKey: may return nil for NSLocaleLanguageCode and
NSLocateCountryCode in certain cases.

This adds a defensive nil check for such cases.

Fixes https://github.com/flutter/flutter/issues/14987, but why?

Without specifying sdkSummary it defaults to vm_outline.dill which is not what we want if using mixins from the sdk. 

* Generate Flutter-specific entry points JSON file while building engine.
* Add ''--tfa' option to front-end server.
* Rename _entryPoint field in front-end server to _mainSource to avoid disambiguation.

This allows blobfs to deduplicate it across {dart,flutter}_{jit,aot}_runner.

* Add more haptic feedback varieties

* Make the specific feedback types do nothing on <iOS 10

This reverts commit 33b88173.

The libtxt font collection cache is consuming too much memory at startup.

* Fix analyzer warning.

  warning • This function declares a return type of 'Future<void>', but doesn't end with a return statement at flutter/frontend_server/lib/server.dart:340:1 • missing_return

* Remove await

* Ignore warning.

* Add an option '--depfile' to produce ninja-style depfile for the generated kernel file.

* Use [program.uriToSource] as a source of dependencies.

When resetting to a null GrVkAlloc alloc use the default ctor instead of the { } initializer. This is needed so an upcoming Skia change doesn't break the flutter build.

This will let other targets depend on the existence of that file.

Previously, a call to Dart_TimelineGetMicros() before a call to
Dart_Initialize() resulted in a crash. This was fixed in
dart-lang/sdk@7434bcad57b567c4b62d48b11b99c323cb245d66.

Related:
* flutter/flutter#4006: SkyShell.app on Mac crashes on startup
* dart-lang/sdk#26486:  [dart_tools_api.h] Dart_TimelineGetMicros crashes on Mac if called before Dart_Initialize

This rename is to prepare for the migration to FIDL2.

* Add option for recompile request to switch to new main file(entrypoint).

This is needed to reuse incremental compiler to compile unrelated programs. First use case is reuse single
incremental compiler for all tests run by 'flutter test'

* Remove left over print

handler.

https://github.com/flutter/flutter/issues/14519

https://github.com/flutter/flutter/issues/14519

It's not an error to request an asset that doesn't exist. In fact, we
request kernel_blob.bin unconditionally at startup, which doesn't
typically exist.