Includes:
* DEPS: Change the URL for Dart to the new Gerrit instance. (https://github.com/flutter/engine/pull/4111)
* Add operators to Radius (https://github.com/flutter/engine/pull/4117)

Fix dropdown buttons menus being clipped by the edge of the screen

* upper case

* fix Russian material translations

* regenerate localizations.dart

This will enable both to be RTL'ed.

Also, factor out common border painting code into paintBorder.
Also, make Border paint uniform non-rounded borders using drawRect.
Also, add some documentation about an issue that wasted an hour of my life.
Also, factor out all the border painting code into TableBorder.paint.

* Allow FloatingActionButton to not have a heroTag.
* Allow FloatingActionButton to not have a child.
* Allow Tooltip to not have a child.
* Improve the debug output of the default FloatingActionButton hero tag.
* Improve the error message in the Hero clashing-tag case.
* Improve the debug output of the Hero widget.
* Improve the debug output of gesture-related widgets.
* Minor improvements to documentation.
* Fix some typos in comments.
* Fix some style nits.

Using anchor links from https://github.com/flutter/website/pull/676

* Allow apps to change the title margin in app bar.

* Fix documentation links and the shouldLayout function in the _ToolbarLayout

* Rename margin to spacing

* review comments

* Test fixes. Now we also test the width to make sure enough space is left for trailing widget

* Expose the middle spacing default and use it in app bar.

* Fix analyzer break

* Doc fixes due to review

* Internationalize the time picker

- header layout and formatting
- 12-hour vs 24-hour dial
- RTL

* make TimeOfDayFormat an enum

* address comments

* Roll engine dependency forward

* Tests seem to fail with segfault. Trying different engine version to troubleshoot

* Tests seem to fail with segfault. Trying original engine version to troubleshoot

* Tests seem to pass with original engine version. Continue bisecting.

* Tests seem to fail now. Continue bisecting.

* Reverted culprit cl, rolling to that

1. Migrate simulator device log tailing to os_log toolchain
2. When the log tag (component) is available (iOS 11/Xcode 9), filter to
   the set of log lines with tag 'Flutter'.

As of iOS 11 / Xcode 9, Flutter engine logs are no longer recorded in the
simulator's syslog file, which we previously read using tail -f. Instead
they're now accessible through Apple's new macOS/iOS os_log facility,
via /usr/bin/log, which supports a relatively flexible query language.

When run in non-interactive mode, /usr/bin/log buffers its output in 4k
chunks, which is significantly smaller than what's emitted up to the
point where the observatory/diagnostics port information is logged. As a
workaround we force it to run in interactive mode via the script tool.

* Trailing widget override for ExpansionTile

Fixes #11890

* Add a test

* Replaced missing comma

Also, remove some redundant error-checking code that never runs
because we're running these scripts with `set -e`.

This ports the five-second retry interval from flutter.bat to the Bash
version. Failures during "pub get" of the flutter tool are common on
Travis and so this should help Travis reliability if nothing else.

* Add --trace-skia parameter to flutter run

Skia tracing is extremely useful for internal debug, but reduces the
amount of space available in the Dart Timeline buffers.
Disable skia tracing by default and expose them via the --trace-skia
flag.

* Roll Engine to 57a1445a45964d386500c39f5e8d06db060abadb

This reverts commit da0602fe.

* Recreate outputFileName completer, handle process launch errors.

* Fix formatting

* Updated comment

* Things lay out but the effects not right yet

* Remaining functionalities and tests

* one line large title only

* Add more docs

* review

This will make it more tractable to convert them for RTL.

Adds a default title to the Title widget, fixes #6802.

* Show accessibility frame while scrolling

* ++

* fix test

Closes https://github.com/flutter/flutter/pull/12049

Update to reflect https://github.com/flutter/flutter/pull/11751 and https://github.com/flutter/website/pull/663

Diagnostics object is.