The Android and iOS versions of this function had diverged. This patch
makes the iOS version match the Android version (and what the framework
expects).

Fixes https://github.com/flutter/flutter/issues/8878

Breaking change: removed facilities for JSON and string messaging from FlutterView/FlutterViewController, leaving only binary messaging there. All other use of flutter communication now goes through FlutterMessageChannel and FlutterMethodChannels. Retained use of String and JSON codecs for now.

Companion flutter PR: flutter/flutter#8837

Fixes buildbot error use of undeclared identifier 'asl_log_message',
which I'm unable to repro locally.

* Perform all iOS logging through ASL

As of iOS 10, ASL is deprecated and replaced with os_log. ASL calls
continue to result in logging but as of iOS 10.3, only ASL_LOG_NOTICE
level and above are logged.

This change partially reverts 2937f06a,
adding back stdout and stderr redirection, which resulted in loss of
some direct writes to stdout that were necessary for debugging.

This change replaces the direct use of syslog with ASL on iOS, which
Apple has stated will continue to log on iOS >= 10. This eliminates the
need for the previous fwd-declaration of syslog.

See https://github.com/flutter/flutter/issues/8635

ASL is deprecated and replaced by os_log() on iOS. As of iOS 10.3,
calling this function breaks our logging altogether. os_log isn't
available pre-iOS 10.0. Rather than implement version checks and
conditional logic, this change eliminates the existing redirection
altogether. All engine code should be logging via the syslog redirection
implemented in Logger_PrintString in dart_runtime_hooks.cc.

Since stdio redirection is eliminated, we eliminate the flag that
controls whether such redirection is enabled.

See https://github.com/flutter/flutter/issues/7561

This property will eventually replace OffsetBase.isInfinite.

See https://github.com/flutter/flutter/issues/4301

* Remove sky_snapshot sources

* update licenses

Names matter, and I apparently forgot to test after adding ' Engine' to
the name. Names can't contain spaces, and must match the filename.

Flutter channels now also supported on iOS. Use FlutterMessageChannel or FlutterMethodChannel with binary/string/json/standard codecs.

* Add podspec to Flutter iOS framework.

Flutter iOS apps are already pod-enabled, so we might as well turn the
engine framework into a pod, so we don't have to manually copy the
current Flutter.framework into the app directory on every build, but
rather let Cocoapods wire things up for us.

For that to happen, we need a pod spec for Flutter.framework. This spec
will not be published, but rather downloaded as part of the engine
artifacts, and the app's Podfile will have a local path dependency on
it.

* Update licenses_golden...

* Roll Dart to 890dff146ac4733018c059b36bc4d67c45da3232

* uddate licenses

* Flutter content handler initializes ICU data when it starts up

* oops, redundant include

* init ICU before getting the font provider

Allow surface size to be passed by caller
temporarily until we get a proper Display API

* roll dart version to pickup fixes in gen_snapshot

* update licenses

See https://github.com/flutter/flutter/issues/8106

New concepts: FlutterMessageChannel (basic message send/receive superseding existing FlutterView methods), FlutterMethodChannel (method invocation and event streams), pluggable codecs for messages and method calls: unencoded binary, string, json, and 'standard' flutter binary encoding.

Do a glFlush after creating textures on the IO thread before they are used by the GPU thread (#3456)

Fixes https://github.com/flutter/flutter/issues/8431

Bug causing roll-back #3454 has been resolved upstream in tonic.

This reverts commit 0a7b177c.

Reason: broke hot reload when using "package:" style imports for
sources within the same project.

Set the TransparentOccluder shadow flag if the color is not opaque

Fixes https://github.com/flutter/flutter/issues/8429

This contains some fixes for Fuchsia and I'd like to keep the version
of Dart used in fuchsia and flutter builds consistent. Should have no
other impactful changes for Flutter.

Mozart ADD, REMOVE and HOVER phases were going through the default value
of Blink's Cancel type, causing inconsistencies.

Bug: US-157