[analyzer] Remove unnecessary non-null assertion util

These assertions are no longer necessary now that the analyzer always runs in sound mode now.

Change-Id: Ie5888c3f424b69fda39d55d442770c51accdc8f9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/424360
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>
Reviewed-by: Samuel Rawlins <[email protected]>

Author: parlough

pkg/analyzer/lib/src/source/package_map_resolver.dart

@@ -6,7 +6,6 @@ import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/source/file_source.dart';
 import 'package:analyzer/source/source.dart';
 import 'package:analyzer/src/generated/source.dart' show UriResolver;
-import 'package:analyzer/src/util/asserts.dart' as asserts;
 import 'package:analyzer/src/utilities/uri_cache.dart';
 import 'package:path/path.dart' as pathos;
 
@@ -28,12 +27,10 @@ class PackageMapUriResolver extends UriResolver {
   /// [packageMap] is a table mapping package names to the paths of the
   /// directories containing the package
   PackageMapUriResolver(this.resourceProvider, this.packageMap) {
-    asserts.notNull(resourceProvider);
-    asserts.notNull(packageMap);
     packageMap.forEach((name, folders) {
       if (folders.length != 1) {
         throw ArgumentError(
-          'Exactly one folder must be specified for a package.'
+          'Exactly one folder must be specified for a package. '
           'Found $name = $folders',
         );
       }

pkg/analyzer/lib/src/util/asserts.dart

@@ -4,7 +4,6 @@
 
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
-import 'asserts_test.dart' as asserts_test;
 import 'either_test.dart' as either_test;
 import 'glob_test.dart' as glob_test;
 import 'lru_map_test.dart' as lru_map_test;
@@ -13,7 +12,6 @@ import 'yaml_test.dart' as yaml_test;
 /// Utility for manually running all tests.
 main() {
   defineReflectiveSuite(() {
-    asserts_test.main();
     either_test.main();
     glob_test.main();
     lru_map_test.main();