Converted legacySafelist to map to avoid using array prototype methods accidently to match with filename

Eg. constructor.js was adding constructor function to aquisition.include which
resulted in the mismatch between typing installer's typeAquisition (which was passed as JSON string and parsed back to null) and one in project
That meant we kept on queuing the new typing installation request.
Fixes microsoft#27435

Author: sheetalkamat

src/server/editorServices.ts

@@ -486,7 +486,7 @@ namespace ts.server {
 
         private readonly hostConfiguration: HostConfiguration;
         private safelist: SafeList = defaultTypeSafeList;
-        private legacySafelist: { [key: string]: string } = {};
+        private readonly legacySafelist = createMap<string>();
 
         private pendingProjectUpdates = createMap<Project>();
         /* @internal */
@@ -638,14 +638,14 @@ namespace ts.server {
                 this.safelist = raw.typesMap;
                 for (const key in raw.simpleMap) {
                     if (raw.simpleMap.hasOwnProperty(key)) {
-                        this.legacySafelist[key] = raw.simpleMap[key].toLowerCase();
+                        this.legacySafelist.set(key, raw.simpleMap[key].toLowerCase());
                     }
                 }
             }
             catch (e) {
                 this.logger.info(`Error loading types map: ${e}`);
                 this.safelist = defaultTypeSafeList;
-                this.legacySafelist = {};
+                this.legacySafelist.clear();
             }
         }
 
@@ -2721,13 +2721,13 @@ namespace ts.server {
                         if (fileExtensionIs(baseName, "js")) {
                             const inferredTypingName = removeFileExtension(baseName);
                             const cleanedTypingName = removeMinAndVersionNumbers(inferredTypingName);
-                            if (this.legacySafelist[cleanedTypingName]) {
+                            const typeName = this.legacySafelist.get(cleanedTypingName);
+                            if (typeName !== undefined) {
                                 this.logger.info(`Excluded '${normalizedNames[i]}' because it matched ${cleanedTypingName} from the legacy safelist`);
                                 excludedFiles.push(normalizedNames[i]);
                                 // *exclude* it from the project...
                                 exclude = true;
                                 // ... but *include* it in the list of types to acquire
-                                const typeName = this.legacySafelist[cleanedTypingName];
                                 // Same best-effort dedupe as above
                                 if (typeAcqInclude.indexOf(typeName) < 0) {
                                     typeAcqInclude.push(typeName);

src/testRunner/unittests/tsserverProjectSystem.ts

@@ -1826,6 +1826,63 @@ namespace ts.projectSystem {
             }
         });
 
+        it("file with name constructor.js doesnt cause issue with typeAcquisition when safe type list", () => {
+            const file1 = {
+                path: "/a/b/f1.js",
+                content: `export let x = 5; import { s } from "s"`
+            };
+            const constructorFile = {
+                path: "/a/b/constructor.js",
+                content: "const x = 10;"
+            };
+            const bliss = {
+                path: "/a/b/bliss.js",
+                content: "export function is() { return true; }"
+            };
+            const host = createServerHost([file1, libFile, constructorFile, bliss, customTypesMap]);
+            let request: string | undefined;
+            const cachePath = "/a/data";
+            const typingsInstaller: server.ITypingsInstaller = {
+                isKnownTypesPackageName: returnFalse,
+                installPackage: notImplemented,
+                inspectValue: notImplemented,
+                enqueueInstallTypingsRequest: (proj, typeAcquisition, unresolvedImports) => {
+                    assert.isUndefined(request);
+                    request = JSON.stringify(server.createInstallTypingsRequest(proj, typeAcquisition, unresolvedImports || server.emptyArray, cachePath));
+                },
+                attach: noop,
+                onProjectClosed: noop,
+                globalTypingsCacheLocation: cachePath
+            };
+
+            const projectName = "project";
+            const projectService = createProjectService(host, { typingsInstaller });
+            projectService.openExternalProject({ projectFileName: projectName, options: {}, rootFiles: toExternalFiles([file1.path, constructorFile.path, bliss.path]) });
+            assert.equal(request, JSON.stringify({
+                projectName,
+                fileNames: [libFile.path, file1.path, constructorFile.path, bliss.path],
+                compilerOptions: { allowNonTsExtensions: true, noEmitForJsFiles: true },
+                typeAcquisition: { include: ["blissfuljs"], exclude: [], enable: true },
+                unresolvedImports: ["s"],
+                projectRootPath: "/",
+                cachePath,
+                kind: "discover"
+            }));
+            const response = JSON.parse(request!);
+            request = undefined;
+            projectService.updateTypingsForProject({
+                kind: "action::set",
+                projectName: response.projectName,
+                typeAcquisition: response.typeAcquisition,
+                compilerOptions: response.compilerOptions,
+                typings: emptyArray,
+                unresolvedImports: response.unresolvedImports,
+            });
+
+            host.checkTimeoutQueueLengthAndRun(2);
+            assert.isUndefined(request);
+        });
+
         it("ignores files excluded by the default type list", () => {
             const file1 = {
                 path: "/a/b/f1.js",