Fix the getCanonicalFileName in sys.ts and also check null value in file watcher call back

Author: zhengbli

src/compiler/sys.ts

@@ -378,7 +378,11 @@ namespace ts {
  */
  function fileEventHandler(eventName: string, relativefileName: string, baseDirPath: Path) {
  // When files are deleted from disk, the triggered "rename" event would have a relativefileName of "undefined"
- const filePath = relativefileName === undefined ? undefined : toPath(relativefileName, baseDirPath, getCanonicalPath);
+ /* tslint:disable:no-null */
+ const filePath = relativefileName === undefined || relativefileName === null
+ ? undefined
+ : toPath(relativefileName, baseDirPath, createGetCanonicalFileName(sys.useCaseSensitiveFileNames));
+ /* tslint:enable:no-null */
  if (eventName === "change" && fileWatcherCallbacks.contains(filePath)) {
  for (const fileCallback of fileWatcherCallbacks.get(filePath)) {
  fileCallback(filePath);
@@ -460,7 +464,7 @@ namespace ts {
  }
 
  function getCanonicalPath(path: string): string {
- return useCaseSensitiveFileNames ? path.toLowerCase() : path;
+ return useCaseSensitiveFileNames ? path : path.toLowerCase();
  }
 
  function readDirectory(path: string, extension?: string, exclude?: string[]): string[] {

src/server/editorServices.ts

@@ -1002,7 +1002,9 @@ namespace ts.server {
  info.setFormatOptions(this.getFormatCodeOptions());
  this.filenameToScriptInfo[fileName] = info;
  if (!info.isOpen) {
- info.fileWatcher = this.host.watchFile(<Path>fileName, _ => { this.watchedFileChanged(fileName); });
+ info.fileWatcher = this.host.watchFile(
+ toPath(fileName, fileName, createGetCanonicalFileName(sys.useCaseSensitiveFileNames)),
+ _ => { this.watchedFileChanged(fileName); });
  }
  }
  }
@@ -1215,7 +1217,9 @@ namespace ts.server {
  }
  }
  project.finishGraph();
- project.projectFileWatcher = this.host.watchFile(<Path>configFilename, _ => this.watchedProjectConfigFileChanged(project));
+ project.projectFileWatcher = this.host.watchFile(
+ toPath(configFilename, configFilename, createGetCanonicalFileName(sys.useCaseSensitiveFileNames)),
+ _ => this.watchedProjectConfigFileChanged(project));
  this.log("Add recursive watcher for: " + ts.getDirectoryPath(configFilename));
  project.directoryWatcher = this.host.watchDirectory(
  ts.getDirectoryPath(configFilename),