Incremental refactoring in index.dart to setup the addition of the missing visitPartOfDirective()

Change-Id: I247db3ad49f928aaec0884aa8d99e603d5a26318
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/106966
Reviewed-by: Jaime Wren <jwren@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Jaime Wren <jwren@google.com>
Auto-Submit: Jaime Wren <jwren@google.com>

Author: jwren

pkg/analyzer/lib/src/dart/analysis/index.dart

@@ -533,9 +533,8 @@ class _IndexContributor extends GeneralizingAstVisitor {
     }
   }
 
-  void recordUriReference(Element element, UriBasedDirective directive) {
-    recordRelation(
-        element, IndexRelationKind.IS_REFERENCED_BY, directive.uri, true);
+  void recordUriReference(Element element, StringLiteral uri) {
+    recordRelation(element, IndexRelationKind.IS_REFERENCED_BY, uri, true);
   }
 
   @override
@@ -603,7 +602,7 @@ class _IndexContributor extends GeneralizingAstVisitor {
   @override
   visitExportDirective(ExportDirective node) {
     ExportElement element = node.element;
-    recordUriReference(element?.exportedLibrary, node);
+    recordUriReference(element?.exportedLibrary, node.uri);
     super.visitExportDirective(node);
   }
 
@@ -632,7 +631,7 @@ class _IndexContributor extends GeneralizingAstVisitor {
   @override
   visitImportDirective(ImportDirective node) {
     ImportElement element = node.element;
-    recordUriReference(element?.importedLibrary, node);
+    recordUriReference(element?.importedLibrary, node.uri);
     super.visitImportDirective(node);
   }
 
@@ -686,7 +685,7 @@ class _IndexContributor extends GeneralizingAstVisitor {
   visitPartDirective(PartDirective node) {
     CompilationUnitElement element = node.element;
     if (element?.source != null) {
-      recordUriReference(element, node);
+      recordUriReference(element, node.uri);
     }
     super.visitPartDirective(node);
   }