DAS: Remove unnecessary getNodeAtOffset helper

There are only two callers, and they each have enough information at
hand to carry out this simple computation themselves.

In particular, getElementAtOffset does not need to reach out to the
driver twice, to get *Result objects for the same file.

Change-Id: Ia5fd1e3045bad4d9aa64a7011a3a5c90db0c305d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/423170
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Samuel Rawlins <[email protected]>

Author: srawlins

pkg/analysis_server/lib/src/analysis_server.dart

@@ -646,28 +646,23 @@ abstract class AnalysisServer {
   /// [offset] of the given [file], or with `null` if there is no node at the
   /// [offset] or the node does not have an element.
   Future<Element2?> getElementAtOffset(String file, int offset) async {
-    if (!priorityFiles.contains(file)) {
-      var driver = getAnalysisDriver(file);
-      if (driver == null) {
-        return null;
-      }
-
-      var unitElementResult = await driver.getUnitElement(file);
-      if (unitElementResult is! UnitElementResult) {
-        return null;
-      }
+    var unitResult = await getResolvedUnit(file);
+    if (unitResult == null) {
+      return null;
+    }
 
+    if (!priorityFiles.contains(file)) {
       var fragment = findFragmentByNameOffset(
-        unitElementResult.fragment,
+        unitResult.libraryFragment,
         offset,
       );
       if (fragment != null) {
         return fragment.element;
       }
     }
 
-    var node = await getNodeAtOffset(file, offset);
-    return getElementOfNode(node);
+    var unit = unitResult.unit;
+    return getElementOfNode(unit.nodeCovering(offset: offset));
   }
 
   /// Returns the element associated with the [node].
@@ -733,18 +728,6 @@ abstract class AnalysisServer {
     }
   }
 
-  /// Return a [Future] that completes with the resolved [AstNode] at the
-  /// given [offset] of the given [file], or with `null` if there is no node as
-  /// the [offset].
-  Future<AstNode?> getNodeAtOffset(String file, int offset) async {
-    var result = await getResolvedUnit(file);
-    var unit = result?.unit;
-    if (unit != null) {
-      return unit.nodeCovering(offset: offset);
-    }
-    return null;
-  }
-
   /// Return the unresolved unit for the file with the given [path].
   ///
   /// Callers should handle [InconsistentAnalysisException] exceptions that may

pkg/analysis_server/lib/src/lsp/handlers/handler_inline_value.dart

@@ -17,6 +17,7 @@ import 'package:analyzer/dart/element/element2.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/source/line_info.dart';
 import 'package:analyzer/src/dart/element/extensions.dart';
+import 'package:analyzer/utilities/extensions/ast.dart';
 
 typedef StaticOptions =
     Either3<bool, InlineValueOptions, InlineValueRegistrationOptions>;
@@ -75,7 +76,7 @@ class InlineValueHandler
       return stoppedOffset.mapResult((stoppedOffset) async {
         // Find the function that is executing. We will only show values for
         // this single function expression.
-        var node = await server.getNodeAtOffset(filePath, stoppedOffset);
+        var node = unitResult.unit.nodeCovering(offset: stoppedOffset);
         var function = node?.thisOrAncestorMatching(
           (node) => node is FunctionExpression || node is MethodDeclaration,
         );