Fix for URI resolution w/ file scheme set in package map.

pkg/analyzer/test/generated/source_factory_test.dart

Index: pkg/analyzer/test/generated/source_factory_test.dart
diff --git a/pkg/analyzer/test/generated/source_factory_test.dart b/pkg/analyzer/test/generated/source_factory_test.dart
index e5109490bf66344fa30f151b76cc75d02d97b09b..7ff5572d1e053a7c09fbb3844389ef6b84dbc926 100644
--- a/pkg/analyzer/test/generated/source_factory_test.dart
+++ b/pkg/analyzer/test/generated/source_factory_test.dart
@@ -77,6 +77,15 @@ void runPackageMapTests() {
       group('resolveUri', () {
         test('URI in mapping', () {
           String uri = resolvePackageUri(config: '''
+unittest:file:///home/somebody/.pub/cache/unittest-0.9.9/lib/
+async:file:///home/somebody/.pub/cache/async-1.1.0/lib/
+quiver:file:///home/somebody/.pub/cache/quiver-1.2.1/lib
+''', uri: 'package:unittest/unittest.dart');
+          expect(uri, equals(
+              '/home/somebody/.pub/cache/unittest-0.9.9/lib/unittest.dart'));
+        });
+        test('URI in mapping (no scheme)', () {
+          String uri = resolvePackageUri(config: '''
 unittest:/home/somebody/.pub/cache/unittest-0.9.9/lib/
 async:/home/somebody/.pub/cache/async-1.1.0/lib/
 quiver:/home/somebody/.pub/cache/quiver-1.2.1/lib