Add multiselect typing for File.openDlg and openDialog (resolve #91)

shared/JavaScript.d.ts

@@ -1499,7 +1499,9 @@ interface FileConstructor {
    * @param filter A filter that limits the types of files displayed in the dialog. In Windows,a filter expression such as "Javascript files:*.jsx;All files:*.*". In Mac OS, a filter function that takes a File instance and returns true if the file should be included in the display, false if it should not.
    * @param multiSelect When true, the user can select multiple files and the return value is an array.
    */
-  openDialog(prompt?: string, filter?: any, multiSelect?: boolean): File
+  openDialog(prompt?: string, filter?: string | Function, multiSelect?: boolean): File | File[]
+  openDialog(prompt: string, filter: string | Function, multiSelect: false): File
+  openDialog(prompt: string, filter: string | Function, multiSelect: true): File[]
 
   /**
    * Opens a dialog so the user can select a file name to save to.
@@ -1689,7 +1691,9 @@ interface File {
    * @param filter A filter that limits the types of files displayed in the dialog. In Windows,a filter expression such as "Javascript files:*.jsx;All files:*.*". In Mac OS, a filter function that takes a File instance and returns true if the file should be included in the display, false if it should not.
    * @param multiSelect When true, the user can select multiple files and the return value is an array.
    */
-  openDlg(prompt?: string, filter?: any, multiSelect?: boolean): File
+  openDlg(prompt?: string, filter?: string | Function, multiSelect?: boolean): File | File[]
+  openDlg(prompt: string, filter: string | Function, multiSelect: false): File
+  openDlg(prompt: string, filter: string | Function, multiSelect: true): File[]
 
   /**
    * Reads the contents of the file, starting at the current position.