Since we've got a vector class, and it has a getter for the magnitude,
why not also a getter for the angle.

To align with `SemanticsAction`.

This reverts commit d8740c70.

Add support for --strong option in the engine, create a strong mode version of the platform file (#4504)

* Add a --strong option to the front end server so we can use strong mode with preview-dart-2.

* Plumb the --strong option through the dart controller into the VM.

* - Build a strong version of platform.dill for use with the engine.
- Fix a strong mode static error in the assert statement

* Enable asserts when running debug version even in strong mode.

* Use the correct platform dill file for linking when doing the aot builds.

* Fix formatting issue.

* Adjust PhysicalModelLayer to use an abstract shape, and provide concrete RRect and Path shape implementations

* add a pushPhysicalShape to scene_builder and compositing.dart

Fixes https://github.com/flutter/flutter/issues/12377.

Reverts the revert in #4448 with fixes to pass on the bot.

This change will require framework changes in flutter/flutter#13490.

This reverts commit 59c3a37e.

* a11y cursor movement by character

* focus fixes

* doc fixes

* Call the ICU bidi API to divide the text into LTR/RTL runs and merge
  them with the styled runs defined by the application
* Maintain a list of glyph positions sorted by the order of the corresponding
  code units in the text, as well as a list of glyphs sorted by x/y coordinates
  in the layout

...by making it know about ALL the deprecated language and region codes.

* Add synchronization to ResourceContext usage

* debug

* Use unique ptr factory

* formatting

* left more notes for future readers

This drops the ViewInsets class in favour of the existing WindowPadding
class for representing the view insets.

Window.viewInsets is the set of window-relative insets that describe the
area of the window that an application may want to treat as effectively
reducing the size of the content. Typically this is due to system UI
that fully obscures underlying content, such as the keyboard.

This area differs from padding in that padding is the set of insets that
describe the area of the window that may be partially (or fully)
obscured by system UI or physical intrusions into the view area (e.g.
iPhone X sensor housing, status bar, or the iPhone X home indicator
widget).

This patch does not yet enable the iOS bottom edge safe area. Once the
framework has been updated to use viewInsets for bottom-edge occlusions
(today, the keyboard), the bottom safe area will be enabled and
framework patches that depend on it, landed.

This keeps the futures chain shorter.

The new ui.Codec API is a superset of the implementation in
image_decoding.cc. While we are not using ui.decodeImageFromList in the
framework anymore, we keep the dart function for backward compatability, and
just make it a thin wrapper around the codec API.

The UIDartState is now always owned by the isolate and always freed in
the isolate cleanup callback.

In the isolate shutdown callback, if the isolate being shut down is the
main isolate, the RuntimeController is informed which in turn notifies
the RuntimeHolder and thus the ApplicationControllerImpl. The
ApplicationControllerImpl tears down the whole Flutter application.

This fixes Fuchsia bug: MI4-328

This retains gamut correction (adjusting colors for screens with different capabilities), but does all blending and interpolation with sRGB-encoded values. That matches the behavior expected by most users, as well as the behavior of nearly all other systems. It also greatly simplifies the EGL code.

A future Skia change will make this behavior more of a first-class citizen, so some of these implementation details will change again, but the behavior will not. The bulk of this change (elimination of complication from the GL surface code) is permanent - it's just the SkColorSpaceXformCanvas that will be replaced.

Adding Rect.expandToInclude and Rect.longestSide to make the Rect API more symmetric.

With the update to HEAD of the Fuchsia buildtools repo, the new clang
toolchain picked up caused link-time breakage in android x86_64
libFlutter.so builds.

Sample log:
https://build.chromium.org/p/client.flutter/builders/Linux%20Engine/builds/1974/steps/build%20android_debug_x64/logs/stdio

Sample failure:
FAILED: libflutter.so libflutter.so.TOC lib.stripped/libflutter.so
../../third_party/android_tools/ndk/toolchains/x86_64-4.9/prebuilt/linux-x86_64/lib/gcc/x86_64-linux-android/4.9.x/../../../../x86_64-linux-android/bin/ld.gold: error: obj/flutter/shell/platform/android/libflutter/android_context_gl.o: unsupported reloc 42 against global symbol std::__ndk1::num_put<char, std::__ndk1::ostreambuf_iterator<char, std::__ndk1::char_traits<char> > >::id

This reverts commit 8ad42f0d.

* Roll Fuchsia buildtools to 85907c59e97527d79bbfdfd849d8e85c24959cc5

This also updates Flutter buildroot to a6e52dbb776c45cc8c57d7143b8eb8b2e762fdfb
which disables -Wtautological-constant-compare temporarily until
https://reviews.llvm.org/D39462 lands in clang. This is in line with
Fuchsia's compiler options.

* Apply clang-format diffs

No logical changes. This applies clang-format from the latest Fuchsia
buildtools to the engine codebase.