Fixes #15198.

* TextFormField/TextField - remove spaces in character counter(follow material design guidelines)

The change in 8b8d368d has only renamed the flag in a subset of the
places.

We were already skipping the check in `flutter upgrade` but this also spawns `flutter precache` and `flutter doctor` which would still check and potentially output the message.

Eliminates 64-bit hardcoding for iOS test apps under dev/. This brings
them in line with the default iOS app templates.

Also, fixes "flutter run" for golden tests, and some docs.

* Eliminate arm64 restriction in iOS framework plist (flutter/engine#5435)
* Roll src/third_party/skia 458f40a..e70c5fb (4 commits) (flutter/engine#5433)
* Call SkAutoCanvasRestore with doSave = true (flutter/engine#5432)

flutter/engine@15ddcd4 Roll src/third_party/skia e45752e..0390d3e (8 commits)
flutter/engine@89eb6a3 call existing ostream operator for SkMatrix
flutter/engine@8360553 Roll src/third_party/skia 588f879..e45752e (24 commits)
flutter/engine@6bfd413 Synchronizes analysis_options.yaml files, and turns on Function typedef lint.

This reverts commit 59bb2dba.

* Pre-Dart SDK roll engine revision

* Dart SDK engine roll for 2018-05-30.

Commits:

3b6caa3517b Split UnresolvedNameGenerator
f50873d3451 [fuchsia] Renaming component FIDL to fuchsia.sys.
13987b073d6 Add Forest method to access the name of a variable
declaration
3b86f823d0a [vm/corelib] Remove GrowableArrayMarker hack.
88127f10e4f Clean up num#toStringAsPrecision docs
1eb1885c62d tools/addlatexhash.dart: Remove unused import
03cb46a2290 [vm/perf] Fix JITDUMP integration.
9d9eff44c99 Support sharing function signatures in deferred parts for
fast startup
ae9f5d2a1b1 Add Forest API for logical expressions
66c590d3ad3 Add json/utf8 BOM support in changelog.
d116e62d76d Improve catch parameter recovery
aa8e2ee178d Revert "[vm] Add tests for determinism of script and AppJIT
snapshots."
ec47e524bc9 Switch to non-alpha versions for analyzer/front_end/kernel.
aac0478fada [vm] Add tests for determinism of script and AppJIT
snapshots.
6cc7aa803a1 Change names/declarations tasks in AnalysisDriver sync.
c30af41b96c Reapply "[mirrors] Add IsolateMirror.loadUri."
a40993a6aff Observatory strong mode fix: Fix incorrect types in
DebuggerStackElement.
0fdfc9aa3b6 Observatory strong mode fix: Add a needed implements clause.
209029ab8ee Observatory strong mode fix: Pass through a type parameter
in the implements clause for GuardedMock.
1d323687b39 Use selection to decide whether EXTRACT_LOCAL_VARIABLE and
EXTRACT_METHOD are available.

This makes it easier to run ios add2app apps with Flutter run.

* Expose Gradient.radial

* cleanup doc

* update tests, null check

* add asset images

flutter/engine@d174c4f Remove unnecessary saveLayer
flutter/engine@b41c2ae Roll src/third_party/skia 137b874..588f879 (6 commits)
flutter/engine@15be13d Roll src/third_party/skia 21ca043..137b874 (5 commits)
flutter/engine@dfb437a Roll src/third_party/skia 264182c..21ca043 (3 commits)
flutter/engine@abda89c Roll src/third_party/skia 09725b0..264182c (1 commits)
flutter/engine@0a47817 Roll src/third_party/skia 61f36d3..09725b0 (1 commits)
flutter/engine@a4f0cd7 Roll src/third_party/skia 8363be1..61f36d3 (8 commits)

This PR adds a SweepGradient class, extending Gradient to expose the engine's ui.Gradient.sweep shader.

Similar to LinearGradient and RadialGradient - SweepGradients can be used in a BoxDecoration or passed to a Paint's shader.

Revert "Update typedef syntax to use Function notation and turn on lint for old notation. (#18035)" (#18041)

This reverts commit 32586020.

Fixes #18028

Just changes typedef declarations, no logic changes.