Fix for resynthesis when a part URI is empty.

pkg/analyzer/test/src/summary/resynthesize_common.dart

Index: pkg/analyzer/test/src/summary/resynthesize_common.dart
diff --git a/pkg/analyzer/test/src/summary/resynthesize_common.dart b/pkg/analyzer/test/src/summary/resynthesize_common.dart
index 38455bc113f2785324e3c30d03c3fcbe5da037be..abd1c184d3717d76e9539330d74be4342dda7d59 100644
--- a/pkg/analyzer/test/src/summary/resynthesize_common.dart
+++ b/pkg/analyzer/test/src/summary/resynthesize_common.dart
@@ -10102,6 +10102,29 @@ class C {
     }
   }
 
+  test_invalidUri_part_emptyUri() {
+    allowMissingFiles = true;
+    var library = checkLibrary(r'''
+part '';
+class B extends A {}
+''');
+    if (isStrongMode) {
+      checkElementText(
+          library,
+          r'''
+class B {
+}
+''');
+    } else {
+      checkElementText(
+          library,
+          r'''
+class B {
+}
+''');
+    }
+  }
+
   test_invalidUris() {
     allowMissingFiles = true;
     var library = checkLibrary(r'''