This reverts commit 2e10a974.

This reverts commit 6a2df7f1.

Snapshots compiled with sound null-safety enabled require changes to the way in
which isolates are launched. Specifically, the `Dart_IsolateFlags::null_safety`
field needs to be known upfront. The value of this field can only be determined
once the kernel snapshot is available. This poses a problem in the engine
because the engine used to launch the isolate at shell initialization and only
need the kernel mappings later at isolate launch (when transitioning the root
isolate to the `DartIsolate::Phase::Running` phase). This patch delays launch of
the isolate on the UI task runner till a kernel mapping is available. The side
effects of this delay (callers no longer having access to the non-running
isolate handle) have been addressed in this patch. The DartIsolate API has also
been amended to hide the method that could return a non-running isolate to the
caller.  Instead, it has been replaced with a method that requires a valid
isolate configuration that returns a running root isolate. The isolate will be
launched by asking the isolate configuration for its null-safety
characteristics.

A side effect of enabling null-safety is that Dart APIs that work with legacy
types will now terminate the process if used with an isolate that has sound
null-safety enabled. These APIs may no longer be used in the engine. This
primarily affects the Dart Convertors in Tonic that convert certain C++ objects
into the Dart counterparts. All known Dart Converters have been updated to
convert C++ objects to non-nullable Dart types inferred using type traits of the
corresponding C++ object. The few spots in the engine that used the old Dart
APIs directly have been manually updated. To ensure that no usage of the legacy
APIs remain in the engine (as these would cause runtime process terminations),
the legacy APIs were prefixed with the `DART_LEGACY_API` macro and the macro
defined to `[[deprecated]]` in all engine translation units. While the engine
now primarily works with non-nullable Dart types, callers can still use
`Dart_TypeToNonNullableType` to acquire nullable types for use directly or with
Tonic. One use case that is not addressed with the Tonic Dart Convertors is the
creation of non-nullable lists of nullable types. This hasn’t come up so far in
the engine.

A minor related change is reworking tonic to define a single library target.
This allows the various tonic subsystems to depend on one another. Primarily,
this is used to make the Dart convertors use the logging utilities. This now
allows errors to be more descriptive as the presence of error handles is caught
(and logged) earlier.

Fixes https://github.com/flutter/flutter/issues/59879

Tweak the primary flutter build rule so that fuchsia is more similar to
other platforms in how tests and the shell are built.

Only embedder_unittests and GLFW tests are disabled on Fuchsia now.

TEST: Ran unittests on host/fuchsia; workstation on fuchsia
BUG: fxb/53847, fxb/54056

Additionally create "_next" permutations for all of the test binaries
on Fuchsia, in order to test both code-paths.

Using the #define follow-up CLs can also create a flutter_runner_next
binary that does not contain any legacy integration code.

BUG: 53847

Added "unrecognized-selector" errors to match g3 builds, added
"overriding-method-mismatch" to catch a common error.

Test failure:

    [ RUN      ] FlutterStringCodec.CanEncodeAndDecodeNil
    2020-04-07 10:21:25.091 flutter_channels_unittests[26965:163315] *** Assertion failure in -[FlutterStringCodec encode:], ../../flutter/shell/platform/darwin/common/framework/Source/FlutterCodecs.mm:36
    2020-04-07 10:21:25.118 flutter_channels_unittests[26965:163315] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: ''
    *** First throw call stack:
    (
    	0   CoreFoundation                      0x00007fff2ccabcf9 __exceptionPreprocess + 256
    	1   libobjc.A.dylib                     0x00007fff5785ea17 objc_exception_throw + 48
    	2   CoreFoundation                      0x00007fff2ccc6a16 +[NSException raise:format:arguments:] + 98
    	3   Foundation                          0x00007fff2ef58e11 -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 194
    	4   flutter_channels_unittests          0x0000000105f1cce2 -[FlutterStringCodec encode:] + 290
    	5   flutter_channels_unittests          0x0000000105f01bbb _ZN45FlutterStringCodec_CanEncodeAndDecodeNil_Test8TestBodyEv + 107
    	6   flutter_channels_unittests          0x00000001081d1732 _ZN7testing8internal38HandleSehExceptionsInMethodIfSupportedINS_4TestEvEET0_PT_MS4_FS3_vEPKc + 146
    	7   flutter_channels_unittests          0x00000001081a76b0 _ZN7testing8internal35HandleExceptionsInMethodIfSupportedINS_4TestEvEET0_PT_MS4_FS3_vEPKc + 128
    	8   flutter_channels_unittests          0x00000001081a75c1 _ZN7testing4Test3RunEv + 209
    	9   flutter_channels_unittests          0x00000001081a8415 _ZN7testing8TestInfo3RunEv + 229
    	10  flutter_channels_unittests          0x00000001081a95aa _ZN7testing9TestSuite3RunEv + 266
    	11  flutter_channels_unittests          0x00000001081b4e43 _ZN7testing8internal12UnitTestImpl11RunAllTestsEv + 995
    	12  flutter_channels_unittests          0x00000001081d8572 _ZN7testing8internal38HandleSehExceptionsInMethodIfSupportedINS0_12UnitTestImplEbEET0_PT_MS4_FS3_vEPKc + 146
    	13  flutter_channels_unittests          0x00000001081b49b3 _ZN7testing8internal35HandleExceptionsInMethodIfSupportedINS0_12UnitTestImplEbEET0_PT_MS4_FS3_vEPKc + 131
    	14  flutter_channels_unittests          0x00000001081b4835 _ZN7testing8UnitTest3RunEv + 197
    	15  flutter_channels_unittests          0x0000000105f22e73 _Z13RUN_ALL_TESTSv + 35
    	16  flutter_channels_unittests          0x0000000105f22d79 main + 553
    	17  libdyld.dylib                       0x00007fff5908c3d5 start + 1
    )
    libc++abi.dylib: terminating with uncaught exception of type NSException
    [ERROR:flutter/fml/backtrace.cc(110)] Caught signal SIGABRT during program execution.
    Frame 0: 0x7fff591316a6 abort
    Frame 1: 0x7fff560ea641 __cxa_bad_cast
    Frame 2: 0x7fff560ea7df default_unexpected_handler()�
    Frame 3: 0x7fff57860ee3 _objc_terminate()�
    Frame 4: 0x7fff560f619e std::__terminate(void (*)())�
    Frame 5: 0x7fff560f5f86 __cxa_get_exception_ptr
    Frame 6: 0x7fff560e8f99 __cxa_get_globals
    Frame 7: 0x7fff5785eb51 objc_exception_throw
    Frame 8: 0x7fff2ccc6a16 +[NSException raise:format:arguments:]
    Frame 9: 0x7fff2ef58e11 -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:]
    Frame 10: 0x105f1cce2 -[FlutterStringCodec encode:]
    Frame 11: 0x105f01bbb FlutterStringCodec_CanEncodeAndDecodeNil_Test::TestBody()�
    Frame 12: 0x1081d1732 void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*)�
    Frame 13: 0x1081a76b0 void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*)�
    Frame 14: 0x1081a75c1 testing::Test::Run()�
    Frame 15: 0x1081a8415 testing::TestInfo::Run()�
    Frame 16: 0x1081a95aa testing::TestSuite::Run()�
    Frame 17: 0x1081b4e43 testing::internal::UnitTestImpl::RunAllTests()�
    Frame 18: 0x1081d8572 bool testing::internal::HandleSehExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*)�
    Frame 19: 0x1081b49b3 bool testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*)�
    Frame 20: 0x1081b4835 testing::UnitTest::Run()�
    Frame 21: 0x105f22e73 RUN_ALL_TESTS()�
    Frame 22: 0x105f22d79 main
    Frame 23: 0x7fff5908c3d5 start

This reverts commit d1c90b42.

"unrecognized-selector" and "overriding-method-mismatch" added as errors.

Ensure that we always pull in the ensure_fuchsia_sdk gn variable.

Fixes breakage introduced in flutter/engine#11016 when building outside
of a Fuchsia tree (e.g. in a stock Flutter engine tree0 on macOS hosts.

When building Fuchsia on macOS hosts, ensure that we reference the
correct clang toolchain path. This patch also prevents bitcode
compilation on Fuchsia tree builds on macOS.

Declare a copy of the enable_bitcode flag within the Flutter build scripts for use in Fuchsia builds (#10003)

enable_bitcode is defined in build/toolchain/clang.gni, which exists in the
Flutter buildroot but not in the Fuchsia source tree.

This converts the libtxt Paragraph and ParagraphBuilder classes into
interfaces with Minikin and SkShaper/SkParagraph based implementations.

Use the --enable-skshaper GN flag to select the Skia shaper implementation
at build time.

This does not actually import the runners into the engine. It only sets up the targets so they need no modifications are necessary when the migration is done. The engine has been verified to build in both buildroots.

This argument has been defunct for a while. It was originally added as a
means of testing the AOT machinery in debug modes.

Adds --dynamic and --interpreter flags to
tools/gn. These flags result in engines with
properties as follows:

--dynamic:
- JIT targeting native code on Android and
  DBC on iOS

--interpreter
- Target DBC even if running on Android.

For example:

gn --android --dynamic --interpreter --runtime-mode release

Will generate an engine:
- Without Dart asserts
- Without Observatory
- With JIT compililation to DBC

into out/android_dynamic_release_dbc

Now lib/ui depends on sky/engine rather than the reverse.

https://github.com/flutter/flutter/issues/4866

We can't quite build it yet because libwtf.a depends on //third_party/icu,
which we don't have yet, but this patch gets us closer.

This include build system changes for selecting Dart's precompiler mode
plus a way to locate and load the precompiled snapshot library from an
Android application

We no longer use IDL.

This matches the behaviour of the Mojo Dart controller and was requested by tonyg@

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1152873006

- New chromium clang rules require explicit external destructors so
  system/lib added for MessagePipe, DataPipe and SharedBuffer
- New chromium clang rules require override and no virtual in
  declarations, so many files updated.
- cc_strip_video patch updated.

BUG=
R=jamesr@chromium.org

Review URL: https://codereview.chromium.org/988693005

We're interested in experimenting with using the DartVM in Sky. This build-time
flag will let us add Dart bindings without disrupting other working going on in
Sky.

R=rafaelw@chromium.org

Review URL: https://codereview.chromium.org/875103002

Change generated by running the following command:

for x in `git ls-files *.gni`; do gn format --in-place $x; done

This came up as an issue in https://codereview.chromium.org/801523002/, but I
didn't want to add noise to that CL.

R=qsr@chromium.org, qsr

Review URL: https://codereview.chromium.org/794413003

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/737793006