Remove redundant import from dev_compiler

Bug: #44569
Change-Id: Iab83d15b0f6c5448b75881fcba8c8ea177feab71
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/213852
Auto-Submit: Samuel Rawlins <[email protected]>
Commit-Queue: Nicholas Shahan <[email protected]>
Reviewed-by: Nicholas Shahan <[email protected]>

Author: srawlins

pkg/dev_compiler/test/expression_compiler/expression_compiler_e2e_suite.dart

@@ -21,7 +21,6 @@ import 'package:front_end/src/fasta/incremental_serializer.dart' as fe;
 import 'package:kernel/ast.dart' show Component, Library;
 import 'package:kernel/target/targets.dart';
 import 'package:path/path.dart' as p;
-import 'package:source_maps/parser.dart' as source_maps;
 import 'package:source_maps/source_maps.dart' as source_maps;
 import 'package:test/test.dart';
 import 'package:webkit_inspection_protocol/webkit_inspection_protocol.dart'