Skip signatures for all mapped types

Mapped and reverse mapped types never have call or construct
signatures, whether or not their members have been resolved, so the
flags alone are enough to answer the question.

Author: jakebailey

tsc/internal/checker/checker.go

@@ -19429,7 +19429,7 @@ func (c *Checker) getSignaturesOfType(t *Type, kind SignatureKind) []*Signature
 }
 
 func (c *Checker) getSignaturesOfStructuredType(t *Type, kind SignatureKind) []*Signature {
-	if t.flags&TypeFlagsStructuredType == 0 || isUnresolvedMappedType(t) {
+	if t.flags&TypeFlagsStructuredType == 0 || t.objectFlags&(ObjectFlagsMapped|ObjectFlagsReverseMapped) != 0 {
 		return nil
 	}
 	resolved := c.resolveStructuredTypeMembers(t)
@@ -19557,13 +19557,6 @@ func (c *Checker) resolveStructuredTypeMembers(t *Type) *StructuredType {
 	return t.AsStructuredType()
 }
 
-// Reports whether t is a mapped type whose members resolveMappedTypeMembers hasn't yet resolved.
-// Mapped types never have signatures, so those needn't be resolved to be known.
-func isUnresolvedMappedType(t *Type) bool {
-	return t.flags&TypeFlagsObject != 0 &&
-		t.objectFlags&(ObjectFlagsReference|ObjectFlagsClassOrInterface|ObjectFlagsReverseMapped|ObjectFlagsAnonymous|ObjectFlagsMapped|ObjectFlagsMembersResolved) == ObjectFlagsMapped
-}
-
 func (c *Checker) resolveObjectTypeMembers(t *Type) {
 	var mapper *TypeMapper
 	var typeParameters []*Type