Auto-roller completed checks. Merging.

* Reland "Roll engine to version b148e628ec86b3a9a0382e0bcfae73f0390a8232 (#20427)"

This is a re-land with downgraded `package:flutter_gallery_assets`
version.

* Downgrade package:flutter_gallery_assets to 0.1.4

* Change engine.version to 81baff97c29bb08cbf8453a3f9042c5813f84ad3 (which contains an additional fix)

* Change engine.version to e3687f70c7ece72000b32ee1b3c02755ba5361ac (since mac tarballs are corrupted on earlier commit)

Reason for revert: The package:flutter_gallery_assets has removed some images which are required for the examples/flutter_gallery, so the gallery build is failing (only discovered after landing, since gallery doesn't seem to get built during github PR presubmit checks)

This CL

  * rolls `engine.version` to flutter/engine@b148e628 (which includes dart sdk 2.1.0-dev)
  * rolls `goldens.version` to flutter/goldens@6c45fafdf (which includes updates due to skia changes in engine)
  * changes `platform.dill` to `platform_strong.dill` in various places due to flutter/engine@a84b210b
  * adds explicit `environment: sdk: ">=2.0.0-dev.68 < 3.0.0"` constraints to `pubspec.yaml` and `pubspec.yaml.tmpl` files (since pub defaults to `<2.0.0` if omitted) 
  * upgrades to newer versions of various 3rd party packages (to ensure transitive dependencies have `<3.0.0` sdk constraint)

This reverts commit 05c2880a.

Auto-roller completed checks. Merging.

This includes the following changes :

e54bc4ea1 Fixed invalid call site of runWithEntrypointAndCallback (#5984)
764884b91 Removed callback for HeadlessDartRunner (#5983)
91537abba Revert "Temporarily add travis/analyze.sh back for Chrome bot (#5961)" (#5966)
3501acb70 Roll src/third_party/skia 9c9611fcc1bb..0d5d0659a684 (7 commits) (#5980)

Includes the following changes :
377793180 Roll Dart to version eab492385c3f345cb2f44f3b702b0e30e4a9c107 (#5979)
8a7af11f7 Fix IsolateStart event kind. (#5978)

Includes the following changes:
78f8bcace Annotate deprecated methods with @Deprecated (#5976)
4c7e5d5a1 Roll src/third_party/skia 0c5b0b1dd692..9c9611fcc1bb (13 commits) (#5977)
4208f8404 make ios text affinity behavior match android (#5971)
69b19a5f5 Roll src/third_party/skia f5402004c4a6..0c5b0b1dd692 (11 commits) (#5975)
8137d3411 Roll src/third_party/skia 4856f5fa596d..f5402004c4a6 (1 commits) (#5974)
cbe960d90 Roll src/third_party/skia 20714bdf90f3..4856f5fa596d (1 commits) (#5973)
f05a4ccaa Roll src/third_party/skia faeef7837210..20714bdf90f3 (11 commits) (#5970)
14af0348b Complete the AndroidView resize call only after a new frame is ready. (#5968)

* Roll engine to 7f083e54fe75

7f083e54f Don't implicitly fall through in switch statement (flutter/engine#5964)
c7ce6dd69 Apply translation to accessibility tree when in landscape (flutter/engine#5950)
aef94b73d Reland "Updated background execution implementation for Android" (flutter/engine#5954)
3421bca7a Roll src/third_party/skia 36216fb0acbc..177742435e52 (15 commits) (flutter/engine#5963)
9d1e67399 Temporarily add travis/analyze.sh back for Chrome bot (flutter/engine#5961)
4386afdaa Roll src/third_party/skia e6d0618f677c..36216fb0acbc (11 commits) (flutter/engine#5960)
7cef3da03 Roll src/third_party/skia 01d9a344b575..e6d0618f677c (1 commits) (flutter/engine#5958)
ad82cb154 Roll src/third_party/skia fdf05f4ff4e9..01d9a344b575 (1 commits) (flutter/engine#5957)
6ea410cfe Revert "Roll Dart to 17b54c76ce9b945c6f013ad08c19268409c0694a (flutter/engine#5955)" (#5956)
f20c58f65 Roll Dart to 17b54c76ce9b945c6f013ad08c19268409c0694a (flutter/engine#5955)
ed1938e99 Roll src/third_party/skia 641ac7daa81c..fdf05f4ff4e9 (3 commits) (flutter/engine#5953)
5f04e00d7 Remove travis directory (flutter/engine#5935)
5442c0a7d Revert "Updated background execution implementation for Android" (flutter/engine#5949)
a5215ce50 Add hasImplicitScrolling SemanticFlag and support in Android bridge (flutter/engine#5941)
4681351af Roll src/third_party/skia 6e487e67a3f3..641ac7daa81c (16 commits) (flutter/engine#5948)
bc885f319 Updated background execution implementation for Android
5770cbd2a Roll src/third_party/skia 12fb9cfeee07..6e487e67a3f3 (8 commits) (flutter/engine#5946)
f4464a8d9 Roll src/third_party/skia 2e77f54f46e8..12fb9cfeee07 (1 commits) (flutter/engine#5945)
c6baaaf75 Replace acquire+release thread annotation with excludes (flutter/engine#5944)
63ede2e35 Roll src/third_party/skia 59aabbcf3b0d..2e77f54f46e8 (1 commits) (flutter/engine#5943)
97aea093e Roll src/third_party/skia 71fe8baccc01..59aabbcf3b0d (1 commits) (flutter/engine#5942)
aaf4a9a24 Roll src/third_party/skia 4c3b63e289c5..71fe8baccc01 (3 commits) (flutter/engine#5940)

* Sync framework changes

ecbb2b28d Call drawPaint instead of drawPath if there's clip (flutter/engine#5937)
597a50849 Roll src/third_party/skia cdfa16d086b8..4c3b63e289c5 (9 commits) (flutter/engine#5936)
715b64ee3 Roll src/third_party/skia 1400d38e0863..cdfa16d086b8 (10 commits) (flutter/engine#5934)
ffbafc852 Flush all embedded Android views on hot restart. (flutter/engine#5929)
9fe6a573e Roll src/third_party/skia 578ef2847b72..1400d38e0863 (7 commits) (flutter/engine#5933)
3b66f20d9 Don't drop MotionEvents with unknown tool type. (flutter/engine#5931)
391ac2f95 Roll src/third_party/skia 64cc576b1fa7..578ef2847b72 (20 commits) (flutter/engine#5930)

Goldens:
64b7a3a Add updated golden files
cb1fa8a Update golden files of PhysicalModel and PhysicalShape
3baed8d Add a goldens package for the embedded Android views integration test.

flutter/engine@76ec93d Add an explicit `-[FlutterViewController init]` implementation
flutter/engine@4893b07 Roll src/third_party/skia e43024a5bab7..64cc576b1fa7 (1 commits)
flutter/engine@aa7326a Roll src/third_party/skia ed8bc196bd56..e43024a5bab7 (1 commits)

flutter/engine@4893b07 Roll src/third_party/skia e43024a5bab7..64cc576b1fa7 (1 commits)
flutter/engine@aa7326a Roll src/third_party/skia ed8bc196bd56..e43024a5bab7 (1 commits)

This roll also switches flutter_tester to use the new minimal ICU data config, which are already in use for app builds. This unifies the ICU data in use. Everything now uses the flutter-specific minimal configuration.

flutter/engine@6929326 Roll ICU to 62.1 and harfbuzz to 1.8.4

flutter/engine@de5f535 Make FML task runner methods virtual so that FXL adaptors in Fuchsia are possible.
flutter/engine@33b4123 Fix sundry Fuchsia build issues after the tonic/fxl migration.
flutter/engine@03a4e53 Update license script & analyze it on CI
flutter/engine@9f9a564 Change CI badge from travis to cirrus
flutter/engine@a61fae0 Dart SDK roll for 8/1/2018
flutter/engine@97e7c6e Roll src/third_party/skia fd98c2c87164..afea9c32acd9 (1 commits)
flutter/engine@1a35c51 Roll src/third_party/skia f4bf7fc35d83..fd98c2c87164 (1 commits)
flutter/engine@8cb0f6d Roll src/third_party/skia 6cfa29738295..f4bf7fc35d83 (2 commits)
flutter/engine@dcd2956 Initial support for more finely-grained a11y features on Window
flutter/engine@83da727 Roll src/third_party/skia 1935aa3d27cd..6cfa29738295 (7 commits)

* Dart SDK roll for 8/1/2018

Dart SDK roll and disabling of return warnings as errors.

List of commits included in this roll:

8bad5c7b29 [vm/compiler] Non-speculative X64 long division/remainder.
918cda18c5 Add docs about sourcemap extensions
329e029bd6 Fixes dart-lang/sdk#34035
12326c10e1 Store constructor field initializera when the target is not a field.
50da4b8d92 Skip ShadowInvalidFieldInitializer while resynthesizing constructor initializers.
8810b6ecc7 Translate kernel.Instantiation in constant expressions.
cb7341fceb Initial support for inlining-data in source-maps.
4206131030 Fix tracking of onStep position of arguments to new expression
384b0a9a73 Issue 34038. Fix resynthesizing imports when mixed with exports.
ba7dbcf412 Update the test output processor to produce more useful analysis
4b2ee8e9a5 Improve catch clause recovery
66500de4dc More fixes to the CFE integration tests
3f2251986d CC sra also in changes to compiler files and tests
4734c55882 Report error on unsupported operators
00e3109368 [VM] Adjust flags for creating depfiles
07c462b471 [vm] Refactoring: extract BaseFlowGraphBuilder to a separate file
ff9167ff7b Fix parseDirectives to recognize metadata
079bebb78b [ VM ] Added missing token position for assert statements
174649b9be [gardening] Update status of dissasemble_test on Windows
8c5aca7d4d Remove the Factory interface
3dc201e168 Update ChangeBuilder to not include empty edits (Take 2)
18047b2757 Refactor test.dart by changing class Configuration to TestConfiguration
7373d38a31 Update status for Dart2js minified CSP on Chrome with fast startup
61148eade8 Update mixin-declaration feature specification.
a98feb0f01 [VM interpreter] Fix exception handling. Convert bytecode indices to pc offsets ....
da2ed2fd59 Don't ignore runtime cast failures on Map<K,V>.
3d8ca8e566 [gardening] Increase debug app-jitk timeout
0313f7bd66 [gardening] Update status file for failing test
6c39bc38f3 Clear ShadowX references that are not required after compilation.
05b9bbd2b5 Remove the dart1 version of the analysis server snapshot.
9107399190 Add back in the analysis server training.
9fb6c09015 Store reference/type for invalid types.
21db860271 Remove non-strong dart2js builders from test_matrix.json
2e7b0a13f1 Add support for accessing all of the created contexts
73663ae7c6 Allow void on the RHS of null coalescing expressions
17cb6d95d1 Don't remember TypeEnvironment in resolution results.
72960de5f9 [VM] Fix one more place where bound error allocation happened on BG thread in new space
6ad79ff4bd Update status file for tests passing under CFE
23ba527735 [VM] Ensure to alloate bound errors in old space on BG compiler
fe8052428b Remove CONTENT_MODIFIED from spec/test for getSignature
c4c847a45c Revert "[CQ] Remove pkg-linux-release from the CQ trybots until it is fixed"
beaf05efa3 [vm] When generating JITDUMP also dump IR and attach it as source to code.
24158b773d [vm/compiler] Do not LICM LoadStaticField for uninitialized fields.
68bfaf3ac3 [vm/compiler] Avoid crashes when canonicalizing unreachable AssertAssignable.
5a45b2a62b [infra] Upgrade homebrew dependencies to work on Dart 2
8e287dc037 [VM] Only add direct implementor when reading script snapshots if ....
6e81d74fcc [VM] Optimize generation of type testing stubs in JIT mode.
058510eeab fix #28233, add hint for missing returns to function expressions
4482d13ff7 [vm/compiler] Bug fix in 64-bit MOD (%) operator.

* Try ignore instead of commenting out.

* Also disable this in package analysis options.

72a38a6b1 Build Android engine in presubmit using Cirrus and GCE (#5882)
f9f40badd Log uncaught exceptions from JNI calls at a higher priority (#5891)
723b2784d Update license script README (#5890)
9420da1e2 Roll src/third_party/skia 9acfc6cac2c6..227424b57d28 (10 commits) (#5888)
27c9de59b Roll src/third_party/skia 55b1e6168454..9acfc6cac2c6 (1 commits) (#5887)
8b8c52ed7 Roll src/third_party/skia b935cf8e12d7..55b1e6168454 (1 commits) (#5886)
89602cc64 [scenic] Expose compositor context from rasterizer. (#5739)
9baeb9c1a Roll src/third_party/skia 5f1dc76d0cec..b935cf8e12d7 (1 commits) (#5885)

This reverts commit e52eeba3.

* Revert "Revert flutter/flutter#19592 (#19861)"

This reverts commit 00aac68e.

* Revert "roll engine to 6f7bdc9fabef810b14577deef5cf330029fd290e (#19848)"

This reverts commit 8b056296.

* Revert "Revert "Roll engine to 7d17da76d (#19785)" (#19792)"

This reverts commit e1a3e1bf.

This reverts commit 8adecb62.

```
7d17da76d Package Skia licenses into a separate file from other third party libraries (#5861)
d2d8bf394 Pass touch events to embedded Android views with dispatchTouchEvents.
216908652 Synthesize Android MotionEvents with the long form obtain method.
0b4432769 Roll src/third_party/skia 396661825f45..1c94a8fabed7 (8 commits) (#5859)
f50e218d9 Rename clip mode to clip behavior (#5853)
42bd86d6d Make the virtual display's presentation window non focusable. (#5845)
a726e1d85 Roll src/third_party/skia c062b6be5a01..396661825f45 (3 commits) (#5857)
3fa83d2d2 Roll src/third_party/skia 15020ea2cf44..c062b6be5a01 (1 commits) (#5856)
75ad43954 Roll src/third_party/skia 4c7a750e5543..15020ea2cf44 (1 commits) (#5855)
5cd8b4530 Roll src/third_party/skia 75e5406be66a..4c7a750e5543 (2 commits) (#5854)
e12b52841 Roll src/third_party/skia b8eeb808d84f..75e5406be66a (17 commits) (#5852)
5bc1e68b6 Remove check_roll from Travis (#5846)
```

95e91e31f Update tonic to pull in Android build fixes. (#5834)
29f475c8d Update tonic to pull in fixes to assertions and build failures on Windows. (#5833)
5474415e1 Roll src/third_party/skia e35055f31c7f..b8eeb808d84f (5 commits) (#5832)
380eb84c4 Remove unused function CreateSkiaInterface (#5812)
33a4aef1d Fix build break caused by https://github.com/flutter/engine/pull/5830 (#5831)
244ebd660 Reapply "Fix Dart 2 reload when running from a snapshot instead of platform.dill." (#5830)
0bad812c7 Migrate to a standalone Tonic repository separated from Topaz (#5817)
f949f7d43 Roll src/third_party/skia 206dbe8a21b6..e35055f31c7f (1 commits) (#5829)
768daa4d3 Roll src/third_party/skia 5e6cd2affe41..206dbe8a21b6 (5 commits) (#5828)
b8cd25b4f libtxt: fix a bug that used incorrect buffer size depending on conditions (#5804)
b7b13b5e9 Roll src/third_party/skia df795638b9bd..5e6cd2affe41 (1 commits) (#5824)
5886949c9 Roll src/third_party/skia dfe1fe40796e..df795638b9bd (1 commits) (#5822)
926f546de Roll src/third_party/skia cc22d4d2fb02..dfe1fe40796e (1 commits) (#5821)
04633f326 Generate process global trace identifiers for pipeline flow traces. (#5818)
fb0bc05d7 Roll src/third_party/skia 6f6de6524c73..cc22d4d2fb02 (1 commits) (#5820)
fadfff7fd Mention that running git clone isn't necessary (#5816)
81ec6000d Roll src/third_party/skia d3509a42638a..6f6de6524c73 (5 commits) (#5819)
2a77a4130 Make git diff range more robust in format.sh (#5813)
e555ea573 Remove trailing white spaces (#5734)
4c7618ac7 Roll src/third_party/skia fa0720436319..d3509a42638a (7 commits) (#5814)

482469bad Roll Dart to 937ee2e8ca4b76499e24cd463f07bfb736bccd74. (#5800)
bb323c145 Revert "Roll src/third_party/skia 9e0d7e4072e4..297c3c8e85bd (62 commits) (#5802)" (#5803)
0bf69f02d Roll src/third_party/skia 9e0d7e4072e4..297c3c8e85bd (62 commits) (#5802)

5d0e13a45 Fix starting isolate directly from CoreJIT snapshot. (#5798)

09ff9493e Re-land removal of vmservice_io from release builds. (#5784)
b523ee847 Revert "Switch to Fuchsia's ICU (#5774)" (#5801)
69695493b Switch to Fuchsia's ICU (#5774)

55b423f07 Ensure assistiveTechnologyEnabled is initialized when the android view is set up (#5793)
3054f3183 Add touch events to the platform views method channel API. (#5796)
91c16af0c Revert "Roll Dart to 937ee2e8ca4b76499e24cd463f07bfb736bccd74. (#5745)" (#5799)
1a66f895b Roll Dart to 937ee2e8ca4b76499e24cd463f07bfb736bccd74. (#5745)
8d046a727 Revert "Roll src/third_party/skia 9e0d7e4072e4..8f8bf8880d9d (32 commits) (#5794)" (#5797)
e8d172cf3 Revert "Fix Dart 2 reload when running from a snapshot instead of platform.dill. (#5792)" (#5795)
624cf7e25 Fix Dart 2 reload when running from a snapshot instead of platform.dill. (#5792)
16da4710d Roll src/third_party/skia 9e0d7e4072e4..8f8bf8880d9d (32 commits) (#5794)
3fe63fd5d Add presubmit check for engine to flutter roll (#5790)

This reverts commit b0eb1632.

This reverts commit 44995dc4.