CQ. Use 'File' for resolveFile() and assertErrorsInFile2()

Replaced a few local helpers with pre-existing global ones.

Change-Id: I40e2955ae353bf0ef7f21388b1f4b06bd08069a7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/352051
Reviewed-by: Brian Wilkerson <[email protected]>
Reviewed-by: Phil Quitslund <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

pkg/analyzer/test/generated/non_hint_code_test.dart

@@ -187,9 +187,8 @@ import 'package:somepackage/other.dart';
 
   Future<void> _assertErrorsInCodeInFile(
       String path, String content, List<ExpectedError> expectedErrors) async {
-    path = convertPath(path);
-    newFile(path, content);
-    result = await resolveFile(path);
+    var file = newFile(path, content);
+    result = await resolveFile(file);
 
     var errorListener = GatheringErrorListener();
     errorListener.addAll(result.errors);

pkg/analyzer/test/src/dart/ast/element_locator_test.dart

@@ -356,7 +356,7 @@ part 'test.dart';
 part of my.lib;
 ''');
 
-    await resolveFile(libFile.path);
+    await resolveFile(libFile);
 
     await resolveFile2(partFile);
     var node = findNode.partOf('part of');

pkg/analyzer/test/src/dart/micro/file_resolution.dart

@@ -118,19 +118,19 @@ class FileResolutionTest with ResourceProviderMixin, ResolutionTest {
 
   @override
   Future<ResolvedUnitResult> resolveFile(
-    String path, {
+    File file, {
     OperationPerformanceImpl? performance,
   }) async {
     result = await fileResolver.resolve(
-      path: path,
+      path: file.path,
       performance: performance,
     );
     return result;
   }
 
   @override
   Future<void> resolveTestFile() async {
-    result = await resolveFile(testFile.path);
+    result = await resolveFile(testFile);
     findNode = FindNode(result.content, result.unit);
     findElement = FindElement(result.unit);
   }