Quick Fix for creating a missing part file.

pkg/analysis_server/lib/src/services/correction/fix_internal.dart

Index: pkg/analysis_server/lib/src/services/correction/fix_internal.dart
diff --git a/pkg/analysis_server/lib/src/services/correction/fix_internal.dart b/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
index a887ed69f0db5253e3c0d24a592a15292fc359bd..9cf28754a4cddc05e9eb74592d67d0561a07fb89 100644
--- a/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
+++ b/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
@@ -134,6 +134,7 @@ class FixProcessor {
     }
     if (errorCode == CompileTimeErrorCode.URI_DOES_NOT_EXIST) {
       _addFix_createImportUri();
+      _addFix_createPartUri();
       _addFix_replaceImportUri();
     }
     if (errorCode == HintCode.DIVISION_OPTIMIZATION) {
@@ -1008,6 +1009,21 @@ class FixProcessor {
     _addFix(FixKind.CREATE_NO_SUCH_METHOD, []);
   }
 
+  void _addFix_createPartUri() {
+    if (node is SimpleStringLiteral && node.parent is PartDirective) {
+      PartDirective partDirective = node.parent;
+      Source source = partDirective.source;
+      if (source != null) {
+        String file = source.fullName;
+        String libName = unitLibraryElement.name;
+        SourceEdit edit = new SourceEdit(0, 0, 'part of $libName;$eol$eol');
+        change.addEdit(file, -1, edit);
+        doSourceChange_addSourceEdit(change, context, source, edit);
+        _addFix(FixKind.CREATE_FILE, [file]);
+      }
+    }
+  }
+
   void _addFix_illegalAsyncReturnType() {
     InterfaceType futureType = context.typeProvider.futureType;
     String futureTypeCode = utils.getTypeSource(futureType, librariesToImport);