Roll flutter 20180322a (#4852)

* Roll dart to af1436931b.

Changes since last dart roll:

```
af1436931b (HEAD, origin/master, origin/HEAD) [CFE] Fix for insertion of duplicate NSM forwarders
48644d5f6a [CFE] Fix crash when trying to add NSM forwarder for a field
898260a998 Split dependency on dart:html from dart:js
ef919c5eb3 fix commit queue: update nSM test expectation on ddc too.
d014fce4de Update dartkp NSM expectations.
6bd38cc912 Analysis Server API for 'Extract Widget' refactoring.
123e59c189 Improve for loop recovery
790b7b98fb [kernel] Update more NSM expectations.
696be0ae46 Initial support for extracting methods.
8d669c9d4e [kernel] Update NSM-forwarding test expectations.
edf039d510 [ VM / Dart 2 ] Made StackMapGC test strong-mode clean. Fixes part of 32190.
77239ee1db [fuchsia] Replace use of deprecated fdio_get_vmo with fdio_get_vmo_clone.
```

* Update license hash. No changes to the licenses

DEPS

@@ -31,7 +31,7 @@ vars = {
   # Dart is: https://github.com/dart-lang/sdk/blob/master/DEPS.
   # You can use //tools/dart/create_updated_flutter_deps.py to produce
   # updated revision list of existing dependencies.
-  'dart_revision': '95e9e890a996b9a61ade6cc81830dd7cf295ec9d',
+  'dart_revision': 'af1436931b93e755d38223c487d33a0a1f5eadf5',
 
   'dart_args_tag': '1.4.1',
   'dart_async_tag': '2.0.6',

travis/licenses_golden/licenses_third_party

-Signature: 93a18f7523d168b169c0648c3927b9c1
+Signature: 53f63598ec036cd96d4a27505157fc0f
 
 UNUSED LICENSES: