Replace indexOf checks with includes() for readability

Modernize membership checks from `indexOf(...) === -1` and
`indexOf(...) >= 0` to use `includes()` in moduleSpecifiers.ts
and importFixes.ts.

https://claude.ai/code/session_01As1r4ZnGpdzw4gMYehgwe7

Author: claude

src/compiler/moduleSpecifiers.ts

@@ -1107,7 +1107,7 @@ function tryGetModuleNameFromExportsOrImports(
     else if (typeof exports === "object" && exports !== null) { // eslint-disable-line no-restricted-syntax
         // conditional mapping
         for (const key of getOwnKeys(exports as MapLike<unknown>)) {
-            if (key === "default" || conditions.indexOf(key) >= 0 || isApplicableVersionedTypesKey(conditions, key)) {
+            if (key === "default" || conditions.includes(key) || isApplicableVersionedTypesKey(conditions, key)) {
                 const subTarget = (exports as MapLike<unknown>)[key];
                 const result = tryGetModuleNameFromExportsOrImports(options, host, targetFilePath, packageDirectory, packageName, subTarget, conditions, mode, isImports, preferTsExtension);
                 if (result) {

src/services/codefixes/importFixes.ts

@@ -607,7 +607,7 @@ function createImportAdderWorker(sourceFile: SourceFile | FutureSourceFile, prog
                 // has named bindings
                 d.importClause?.namedBindings &&
                 // is not being fully removed
-                emptyImportDeclarations.indexOf(d) === -1 &&
+                !emptyImportDeclarations.includes(d) &&
                 // is not gaining named imports
                 !addToExisting.get(d.importClause)?.namedImports &&
                 // all named imports are being removed
@@ -632,8 +632,8 @@ function createImportAdderWorker(sourceFile: SourceFile | FutureSourceFile, prog
                 const importDeclaration = findAncestor(declaration, isImportDeclaration);
                 if (
                     importDeclaration &&
-                    emptyImportDeclarations.indexOf(importDeclaration) === -1 &&
-                    namedBindingsToDelete.indexOf(importDeclaration) === -1
+                    !emptyImportDeclarations.includes(importDeclaration) &&
+                    !namedBindingsToDelete.includes(importDeclaration)
                 ) {
                     if (declaration.kind === SyntaxKind.ImportClause) {
                         changeTracker.delete(sourceFile, declaration.name!);