Merge pull request #31377 from microsoft/noThisParameterFiltering

Revert this-parameter filtering in completions

Author: ahejlsberg

src/compiler/checker.ts

@@ -20386,25 +20386,8 @@ namespace ts {
         }
 
         function isValidPropertyAccessForCompletions(node: PropertyAccessExpression | ImportTypeNode | QualifiedName, type: Type, property: Symbol): boolean {
-            return isValidPropertyAccessWithType(node, node.kind === SyntaxKind.PropertyAccessExpression && node.expression.kind === SyntaxKind.SuperKeyword, property.escapedName, type)
-                && (!(property.flags & SymbolFlags.Method) || isValidMethodAccess(property, type));
-        }
-        function isValidMethodAccess(method: Symbol, actualThisType: Type): boolean {
-            const propType = getTypeOfPropertyOfType(actualThisType, method.escapedName)!;
-            const signatures = getSignaturesOfType(getNonNullableType(propType), SignatureKind.Call);
-            Debug.assert(signatures.length !== 0);
-            return signatures.some(sig => {
-                const signatureThisType = getThisTypeOfSignature(sig);
-                return !signatureThisType || isTypeAssignableTo(actualThisType, getInstantiatedSignatureThisType(sig, signatureThisType, actualThisType));
-            });
-        }
-        function getInstantiatedSignatureThisType(sig: Signature, signatureThisType: Type, actualThisType: Type): Type {
-            if (!sig.typeParameters) {
-                return signatureThisType;
-            }
-            const context = createInferenceContext(sig.typeParameters, sig, InferenceFlags.None);
-            inferTypes(context.inferences, actualThisType, signatureThisType);
-            return instantiateType(signatureThisType, createSignatureTypeMapper(sig, getInferredTypes(context)));
+            return isValidPropertyAccessWithType(node, node.kind === SyntaxKind.PropertyAccessExpression && node.expression.kind === SyntaxKind.SuperKeyword, property.escapedName, type);
+            // Previously we validated the 'this' type of methods but this adversely affected performance. See #31377 for more context.
         }
 
         function isValidPropertyAccessWithType(