This adds support to PlatformViewLayer for handling hover events. Prior
to this, PlatformViewLayers only supported events forwarded by the
gesture recognizers associated with the PlatformViewRenderBox. Hover
events don't participate in gesture recognition and as such are dropped
in GestureBinding. That said, hover event processing in platform views
is expected for desktop and other platforms with hover event support.

This adds support for passing an optional MouseTrackerAnnotation to
PlatformViewLayer. PlatformViewRenderBox populates this with a mouse
tracker annotation that forwards hover events to
PlatformViewController.dispatchPointerEvent() for handling by users.

Introduced LargeImageHandler to ImageCache class.

This normalizes all of the "See also" blocks in comments so that they conform in style.

They all look like this now:

  /// See also:
  ///
  ///  * [MyFavoriteWidget], because it's cool.
  class Foo {}

I removed some useless "See also" blocks, and added commentary to ones that were just "bare" references.

This is my penance for adding so many bullets that are "-" instead of "*". :-)

This reverts commit 2a113165.

This adds actions and shortcuts arguments to WidgetsApp (and MaterialApp and CupertinoApp) to allow developers to override the default mappings on an application, and to allow for a more complex definition of the default mappings.

I've stopped using SelectAction here, in favor of using ActivateAction for all activations, but haven't removed it, to avoid a breaking change, and to allow a common base class for these types of actions. This is because some platforms use the same mapping (web) for both kinds of activations (both select and activate).

git@github.com:flutter/engine.git/compare/07aab98212cb...fdaa7cf12175

git log 07aab98212cb..fdaa7cf12175 --first-parent --oneline
2019-12-04 skia-flutter-autoroll@skia.org Roll fuchsia/sdk/core/mac-amd64 from OSk8h... to XCAOU... (#14128)
2019-12-04 skia-flutter-autoroll@skia.org Roll src/third_party/skia 75368c3a0290..ccca30aad770 (12 commits) (#14129)


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Adds a manual test that allows testing of density for buttons. Also updates some of the button tests to be somewhat simpler and to test the child positions in the test to make sure they are consistent.

git@github.com:flutter/engine.git/compare/1cdfc99314df...07aab98212cb

git log 1cdfc99314df..07aab98212cb --first-parent --oneline
2019-12-04 brianosman@google.com Fix one more use of deprecated path fill type API (#14127)


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* Api Samples and Diagrams for the following classes and methods:

  - AlertDialog
  - SimpleDialog
  - SingleChildScrollView
  - showDatePicker
  - RichText
  - InputDecoration
  - Divider
  - StreamBuilder
  - DataTable
  - BottomSheet
    - showBottomSheet
    - showModalBottomSheet

* Update packages/flutter/lib/src/material/divider.dart
Co-Authored-By: Kate Lovett <katelovett@google.com>

* Update packages/flutter/lib/src/widgets/basic.dart
Co-Authored-By: Kate Lovett <katelovett@google.com>

* Update packages/flutter/lib/src/material/data_table.dart
Co-Authored-By: Kate Lovett <katelovett@google.com>

* Update packages/flutter/lib/src/material/bottom_sheet.dart
Co-Authored-By: Kate Lovett <katelovett@google.com>

* Update packages/flutter/lib/src/material/scaffold.dart
Co-Authored-By: Kate Lovett <katelovett@google.com>

* Move animation out of sample

* Remove "widget.size", replace with "60"

* implicit-casts:false in flutter_driver

* address review comments

* implicit-casts:false in flutter/lib/src/rendering

* address review comments

* implicit-casts:false in flutter/lib/src/widgets

* address review comments

* address review comment

1cdfc9931 Roll src/third_party/dart 19fc1016da..2a13b1fe26 (6 commits) (flutter/engine#14107) (#46059)


git@github.com:flutter/engine.git/compare/3e6d6bc612fd...1cdfc99314df

git log 3e6d6bc612fd..1cdfc99314df --first-parent --oneline
2019-12-04 bkonyi@google.com Roll src/third_party/dart 19fc1016da..2a13b1fe26 (6 commits) (#14107)


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git@github.com:flutter/engine.git/compare/90e28c027c0b...3e6d6bc612fd

git log 90e28c027c0b..3e6d6bc612fd --first-parent --oneline
2019-12-04 47866232+chunhtai@users.noreply.github.com add pointer data santizing in flutter web engine (#14082)


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This is a follow-on to #45455 - the test failures indicated a
real problem, so re-enabling the tests on non-master.

https://github.com/flutter/flutter/issues/45453

* Add a density attribute to ThemeData

* Simplify tests

* Review changes (Hans)

git@github.com:flutter/engine.git/compare/617938024315...90e28c027c0b

git log 617938024315..90e28c027c0b --first-parent --oneline
2019-12-04 bkonyi@google.com Roll src/third_party/dart 89e31069e8..19fc1016da (6 commits) (#14093)
2019-12-03 dworsham@google.com Relanding: Add Flow unittests and fixtures (#14091)
2019-12-03 bkonyi@google.com Roll src/third_party/dart a4d799c402..89e31069e8 (14 commits) (#14089)


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git@github.com:flutter/engine.git/compare/1a96087747ac...617938024315

git log 1a96087747ac..617938024315 --first-parent --oneline
2019-12-03 caseyhillers@gmail.com Update fallback to Roboto url to be HTTPS (#14086)
2019-12-03 iska.kaushik@gmail.com Revert "Fix fml_unittests (#14062)" (#14087)
2019-12-03 liyuqian@google.com Revert PRs to unblock David and Jim's work (#14088)
2019-12-03 skia-flutter-autoroll@skia.org Roll fuchsia/sdk/core/mac-amd64 from 6QxEZ... to OSk8h... (#14085)
2019-12-03 bkonyi@google.com Roll src/third_party/dart e4344a568f..a4d799c402 (7 commits) (#14083)


If this roll has caused a breakage, revert this CL and stop the roller
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To report a problem with the AutoRoller itself, please file a bug:
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