Use DartType.getDisplayString() instead of toString().

Change-Id: I982a4fff312593e6788afcbc9200a83793fefb97
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/134464
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

Author: scheglov

pkg/analysis_server/lib/src/protocol_server.dart

@@ -62,15 +62,16 @@ String getReturnTypeString(engine.Element element) {
     if (element.kind == engine.ElementKind.SETTER) {
       return null;
     } else {
-      return element.returnType?.toString();
+      return element.returnType?.getDisplayString(withNullability: false);
     }
   } else if (element is engine.VariableElement) {
     engine.DartType type = element.type;
     return type != null
         ? type.getDisplayString(withNullability: false)
         : 'dynamic';
   } else if (element is engine.FunctionTypeAliasElement) {
-    return element.function.returnType.toString();
+    var returnType = element.function.returnType;
+    return returnType.getDisplayString(withNullability: false);
   } else {
     return null;
   }

pkg/analysis_server/lib/src/search/type_hierarchy.dart

@@ -119,8 +119,10 @@ class TypeHierarchyComputer {
     {
       String displayName;
       if (typeArguments != null && typeArguments.isNotEmpty) {
-        displayName =
-            classElement.displayName + '<' + typeArguments.join(', ') + '>';
+        var typeArgumentsStr = typeArguments
+            .map((type) => type.getDisplayString(withNullability: false))
+            .join(', ');
+        displayName = classElement.displayName + '<' + typeArgumentsStr + '>';
       }
       ExecutableElement memberElement = _findMemberElement(classElement);
       item = TypeHierarchyItem(convertElement(classElement),

pkg/analysis_server/lib/src/services/completion/dart/utilities.dart

@@ -332,7 +332,7 @@ String nameForType(SimpleIdentifier identifier, TypeAnnotation declaredType) {
   if (type == null) {
     return DYNAMIC;
   }
-  return type.toString();
+  return type.getDisplayString(withNullability: false);
 }
 
 /// TODO(pq): fix to use getDefaultStringParameterValue()

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

@@ -1426,7 +1426,7 @@ class FixProcessor extends BaseProcessor {
               changeBuilder,
               DartFixKind.CHANGE_TYPE_ANNOTATION,
               args: [
-                typeNode.type,
+                typeNode.type.getDisplayString(withNullability: false),
                 newType.getDisplayString(withNullability: false),
               ],
             );