Roll src/third_party/dart 5fad012..892fcf2 (15 commits)

dart-lang/sdk@892fcf2c45 Avoid constructing RegExp for every BigInt.tryParse
dart-lang/sdk@b4751d5e16 [vm/ffi] Pointer.asExternalTypedData to extension method - Fix Flutter
dart-lang/sdk@91c6dc15de [vm/ffi] Pointer.asExternalTypedData to extension method
dart-lang/sdk@545a06b19e Fix typo in zone documentation.
dart-lang/sdk@1e3cbd4344 Migration: Add IndexExpression support to FixBuilder.
dart-lang/sdk@5594981c2a Migration: add isCompound parameter to FixBuilder.visitAssignmentTarget.
dart-lang/sdk@13f6d8213b Migration: add FixBuilder support for prefix/postfix expressions.
dart-lang/sdk@0121a1fce1 Migration: finish EdgeBuilder support for prefix/postfix expressions.
dart-lang/sdk@d2f9e83861 Migration: integrate flow analysis of `??` into FixBuilder
dart-lang/sdk@04d800af49 Migration: add fixBuilder support for throw and conditional expressions
dart-lang/sdk@4f4d1bdf10 Migration: Add if-statement and block-statement support to FixBuilder.
dart-lang/sdk@27967490f6 Migration: add FixBuilder support for typed lists of expressions.
dart-lang/sdk@14d4b93349 Migration: update FixBuilder to handle simple statements.
dart-lang/sdk@61790a17b6 Flow analysis: add support for non-null assertion operator.
dart-lang/sdk@4e9220efdb Flow analysis: change the way parenthesized expressions are handled.

DEPS

@@ -34,7 +34,7 @@ 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': '5fad012d02fe34b25f027646367584cb37903850',
+  'dart_revision': '892fcf2c4586bc00a23c19ddfd8be0064681ad05',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py

ci/licenses_golden/licenses_third_party

@@ -1,4 +1,4 @@
-Signature: 9ebcf3a6a86b2e9e59e599df71cb1d63
+Signature: 9a0c37be72b79ca992df659fd575eff8
 
 UNUSED LICENSES: