message: Stop caching the root file for every workspace
diff: @@ -84,10 +84,9 @@ export class Manager {
  */
  private readonly cachedContent = Object.create(null) as Content
  - private readonly localRootFiles = Object.create(null) as { [key: string]: string | undefined }
  - private readonly rootFilesLanguageIds = Object.create(null) as { [key: string]: string | undefined }
  - // Store one root file for each workspace.
  - private readonly rootFiles = Object.create(null) as { [key: string]: RootFileType | undefined }
  + private _localRootFile: string | undefined
  + private _rootFilesLanguageId: string | undefined
  + private _rootFile: RootFileType | undefined
  private workspaceRootDirUri: string = ''
  private readonly extension: Extension
  @@ -187,7 +186,7 @@ export class Manager {
  * It is `undefined` before `findRoot` called.
  */
  get rootFile(): string | undefined {
  - const ret = this.rootFiles[this.workspaceRootDirUri]
  + const ret = this._rootFile
  if (ret) {
  if (ret.type === 'filePath') {
  return ret.filePath
  @@ -206,14 +205,14 @@ export class Manager {
  set rootFile(root: string | undefined) {
  if (root) {
  - this.rootFiles[this.workspaceRootDirUri] = { type: 'filePath', filePath: root }
  + this._rootFile = { type: 'filePath', filePath: root }
  } else {
  - this.rootFiles[this.workspaceRootDirUri] = undefined
  + this._rootFile = undefined
  }
  }
  get rootFileUri(): vscode.Uri | undefined {
  - const root = this.rootFiles[this.workspaceRootDirUri]
  + const root = this._rootFile
  if (root) {
  if (root.type === 'filePath') {
  return vscode.Uri.file(root.filePath)
  @@ -234,23 +233,23 @@ export class Manager {
  rootFile = { type: 'uri', uri: root }
  }
  }
  - this.rootFiles[this.workspaceRootDirUri] = rootFile
  + this._rootFile = rootFile
  }
  get localRootFile() {
  - return this.localRootFiles[this.workspaceRootDirUri]
  + return this._localRootFile
  }
  set localRootFile(localRoot: string | undefined) {
  - this.localRootFiles[this.workspaceRootDirUri] = localRoot
  + this._localRootFile = localRoot
  }
  get rootFileLanguageId() {
  - return this.rootFilesLanguageIds[this.workspaceRootDirUri]
  + return this._rootFilesLanguageId
  }
  set rootFileLanguageId(id: string | undefined) {
  - this.rootFilesLanguageIds[this.workspaceRootDirUri] = id
  + this._rootFilesLanguageId = id
  }
  getWorkspaceRootDirUri(): vscode.Uri | undefined {
  