Added docs examples of getting the string from a TextField

The transition_perf test is no longer flaky.

228907272 Roll src/third_party/skia d545bfbb94ca..dd0dff1c35d2 (25 commits) (flutter/engine#12334) (#40761)


git@github.com:flutter/engine.git/compare/fce8be3a68c0...2289072724ff

git log fce8be3a68c0..2289072724ff --no-merges --oneline
2019-09-18 skia-flutter-autoroll@skia.org Roll src/third_party/skia d545bfbb94ca..dd0dff1c35d2 (25 commits) (flutter/engine#12334)


If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC stuartmorgan@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

git@github.com:flutter/engine.git/compare/36be89da497b...fce8be3a68c0

git log 36be89da497b..fce8be3a68c0 --no-merges --oneline
2019-09-18 bkonyi@google.com Roll src/third_party/dart f22f62c85d..cb80ea7ba9 (8 commits)


If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC stuartmorgan@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

git@github.com:flutter/engine.git/compare/6a96417416b4...36be89da497b

git log 6a96417416b4..36be89da497b --no-merges --oneline
2019-09-17 matthew-carroll@users.noreply.github.com Added javadoc comments to FlutterActivity and FlutterFragmentActivity. (flutter/engine#12328)
2019-09-17 bkonyi@google.com Roll src/third_party/dart 7505b3a5f0..f22f62c85d (5 commits)
2019-09-17 iska.kaushik@gmail.com Revert "Provide dart vm initalize isolate callback so that children isolates belong to parent's isolate group. (#9888)" (flutter/engine#12327)
2019-09-17 ankitdave06@gmail.com [flutter] Remove old A11y API's. (flutter/engine#12308)


If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC stuartmorgan@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

git@github.com:flutter/engine.git/compare/d1692d4cc703...6a96417416b4

git log d1692d4cc703..6a96417416b4 --no-merges --oneline
2019-09-17 skia-flutter-autoroll@skia.org Roll fuchsia/sdk/core/linux-amd64 from RRgw-... to F-g18... (flutter/engine#12326)
2019-09-17 chinmaygarde@google.com Account for root surface transformation on the surfaces managed by the external view embedder. (flutter/engine#11384)
2019-09-17 matthew-carroll@users.noreply.github.com Introduce FlutterFragmentActivity (flutter/engine#12305)
2019-09-17 chinmaygarde@google.com Shuffle test order and repeat test runs once. (flutter/engine#12275)


If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC stuartmorgan@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

git@github.com:flutter/engine.git/compare/63873d9f421f...d1692d4cc703

git log 63873d9f421f..d1692d4cc703 --no-merges --oneline
2019-09-17 hterkelsen@users.noreply.github.com Update canvaskit backend (flutter/engine#12318)
2019-09-17 mouad.debbar@gmail.com README for the felt tool (flutter/engine#12323)
2019-09-17 jason-simmons@users.noreply.github.com Fix continuous event polling in the GLFW event loop (flutter/engine#12320)
2019-09-17 15365765+rafern@users.noreply.github.com Tests for #11283 (flutter/engine#12322)
2019-09-17 ditman@gmail.com Improve check to render (or not) a DRRect when inner falls outside of outer on RecordingCanvas (flutter/engine#12229)
2019-09-17 bkonyi@google.com Roll src/third_party/dart dd1969a43a..7505b3a5f0 (39 commits)
2019-09-17 30870216+gaaclarke@users.noreply.github.com Channel buffers (flutter/engine#12167)
2019-09-17 xster@google.com Make iOS FlutterViewController stop sending inactive/pause on app lifecycle events when not visible (flutter/engine#12128)
2019-09-17 stuartmorgan@google.com Adds PluginRegistry to the C++ client wrapper API (flutter/engine#12287)
2019-09-17 liyuqian@google.com Add "type" to getDisplayRefreshRate protocol (flutter/engine#12319)
2019-09-17 mouad.debbar@gmail.com Add a build command to felt (flutter/engine#12303)
2019-09-17 skia-flutter-autoroll@skia.org Roll src/third_party/skia df432d5efb70..d545bfbb94ca (1 commits) (flutter/engine#12316)
2019-09-17 skia-flutter-autoroll@skia.org Roll fuchsia/sdk/core/linux-amd64 from rwf0-... to RRgw-... (flutter/engine#12315)
2019-09-17 skia-flutter-autoroll@skia.org Roll src/third_party/skia f8486f2c5fb6..df432d5efb70 (1 commits) (flutter/engine#12313)
2019-09-17 skia-flutter-autoroll@skia.org Roll src/third_party/skia b47704b0bd34..f8486f2c5fb6 (2 commits) (flutter/engine#12312)
2019-09-16 jason-simmons@users.noreply.github.com Fix the declaration of setSystemGestureExclusionRects to match the PlatformMessageHandler interface (flutter/engine#12306)
2019-09-16 gw280@google.com Manage resource and onscreen contexts using separate IOSGLContext objects (flutter/engine#12277)
2019-09-16 goderbauer@google.com Cleanup in web_ui (flutter/engine#12307)
2019-09-16 30870216+gaaclarke@users.noreply.github.com Made flutter startup faster by allowing initialization to be parallelized (flutter/engine#10182)
2019-09-16 skia-flutter-autoroll@skia.org Roll src/third_party/skia c22498502cda..b47704b0bd34 (16 commits) (flutter/engine#12304)
2019-09-16 jonahwilliams@google.com Include firefox in check to quote font families (flutter/engine#12288)
2019-09-16 bkonyi@google.com Roll src/third_party/dart 7799f424f4..dd1969a43a (2 commits)


If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC stuartmorgan@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

Previously, focus nodes created in the tab scaffold were not being disposed of properly, causing possible memory leaks. Also, the builder wasn't being passed the right context so that the FocusScope.of operator inside of a builder would find the focus scope for the given tab (it was being passed the context of the overall tab scaffold).

This reverts commit 6ad88bd5.

This updates the keyboard maps to use updated HID codes for game controller buttons (from Chrome), and to encode that GLFW "super" keys are what we call "meta" keys (i.e. Windows key or Command key).

* Extract some onPress methods

* address review comments

Add the option to configure a chip check mark color

Moves the generated config into that directory. Matches the structure of
the other desktop projects.

Also fixes #40265

git@github.com:flutter/engine.git/compare/8a8610a9a514...63873d9f421f

git log 8a8610a9a514..63873d9f421f --no-merges --oneline
2019-09-16 15365765+rafern@users.noreply.github.com Fix objects equal to null not being detected as null (flutter/engine#11283)
2019-09-16 qxyat2019@gmail.com Reset NSNetService delegate to nil，when stop service. (flutter/engine#11270)


If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC jimgraham@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

This reverts commit af9f424d.

Reverts flutter/flutter#39439

Reason: this passed the local device lab test on my Macbook but it failed in the actual device lab. Will investigate, fix, and reland.

TBR: @dnfield @goderbauer @tvolkert @Hixie 

git@github.com:flutter/engine.git/compare/2c4ed36c60ae...8a8610a9a514

git log 2c4ed36c60ae..8a8610a9a514 --no-merges --oneline
2019-09-16 liyuqian@google.com Implement Base32Decode (flutter/engine#12253)
2019-09-16 liyuqian@google.com Reland "Smooth out iOS irregular input events delivery (#11817)" (flutter/engine#12280)
2019-09-16 mouad.debbar@gmail.com Refactor and polish the 'felt' tool (flutter/engine#12258)


If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC jimgraham@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

* Fixing LocalFileComparator output

* Fixing path separators for windows failures

* Windows path issues

* Testing

* ++

* ++

* Fixing base directory - windows

* Clean up

For https://github.com/flutter/flutter/issues/33899

Test added:
- simple_animation_perf_ios

Test modified:
- backdrop_filter_perf_ios__timeline_summary

We'll add the CPU/GPU measurement to more iOS tests
once it's proven to be non-flaky.

git@github.com:flutter/engine.git/compare/04f567bdde40...2c4ed36c60ae

git log 04f567bdde40..2c4ed36c60ae --no-merges --oneline
2019-09-16 bkonyi@google.com Roll src/third_party/dart a8f433820b..7799f424f4 (3 commits)
2019-09-16 goderbauer@google.com a11y: expose max character count for text fields (flutter/engine#12269)
2019-09-16 skia-flutter-autoroll@skia.org Roll src/third_party/skia 86c48abc94f3..c22498502cda (1 commits) (flutter/engine#12300)


If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC jimgraham@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

04f567bdd Do not assume Platform.script is a Dart source file during training. (flutter/engine#12256) (#40603)


git@github.com:flutter/engine.git/compare/aef8f5e01a91...04f567bdde40

git log aef8f5e01a91..04f567bdde40 --no-merges --oneline
2019-09-16 rmacnak@google.com Do not assume Platform.script is a Dart source file during training. (flutter/engine#12256)


If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC jimgraham@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

git@github.com:flutter/engine.git/compare/3da554934b84...aef8f5e01a91

git log 3da554934b84..aef8f5e01a91 --no-merges --oneline
2019-09-16 bkonyi@google.com Roll src/third_party/dart f8f0b845c2..a8f433820b (1 commits)


If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC jimgraham@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

3da554934 Roll fuchsia/sdk/core/linux-amd64 from Ha3yC... to rwf0-... (flutter/engine#12298) (#40588)


git@github.com:flutter/engine.git/compare/8749d1722961...3da554934b84

git log 8749d1722961..3da554934b84 --no-merges --oneline
2019-09-16 skia-flutter-autoroll@skia.org Roll fuchsia/sdk/core/linux-amd64 from Ha3yC... to rwf0-... (flutter/engine#12298)


If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC jimgraham@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md