Roll src/third_party/dart 8e4dcf48c4..aacc0b0709 (4 commits)

aacc0b0709 Index more declarations and build more scopes.
b2df6eddda Make a new "nullability node" abstraction for the migration tool.
258d2f121b Rewrite more element model to using AST.
27a58d455d [vm/aot] Remove special casing of td views, allow external/internal typed data to be fast as well in string decoding

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': '8e4dcf48c4bb64beaf930b3f85f6e4d01b570203',
+  'dart_revision': 'aacc0b07098231ff2051cbc7b40c932171caaddb',
 
   # 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

-Signature: 0b65326c10b07fe94aff5d5d32b01635
+Signature: 18193ae58a638fba93466a2ff63b69b6
 
 UNUSED LICENSES: