add JS support the using keyword

javascript/ql/lib/semmle/javascript/PrintAst.qll

@@ -246,13 +246,15 @@ private module PrintJavaScript {
     }
 
     /**
-     * Gets "var" or "const" or "let" depending on what type of declaration `decl` is.
+     * Gets "var" or "const" or "let" or "using" depending on what type of declaration `decl` is.
      */
     private string getDeclarationKeyword(DeclStmt decl) {
       decl instanceof VarDeclStmt and result = "var"
       or
       decl instanceof ConstDeclStmt and result = "const"
       or
+      decl instanceof UsingDeclStmt and result = "using"
+      or
       decl instanceof LetStmt and result = "let"
     }
   }

javascript/ql/lib/semmle/javascript/Stmt.qll

@@ -1041,6 +1041,17 @@ class VarDeclStmt extends @var_decl_stmt, DeclStmt { }
  */
 class ConstDeclStmt extends @const_decl_stmt, DeclStmt { }
 
+/**
+ * A `using` declaration statement.
+ *
+ * Example:
+ *
+ * ```
+ * using file = new TextFile("file.txt");
+ * ```
+ */
+class UsingDeclStmt extends @using_decl_stmt, DeclStmt { }
+
 /**
  * A `let` declaration statement.
  *

javascript/ql/lib/semmlecode.javascript.dbscheme

@@ -162,9 +162,10 @@ case @stmt.kind of
 | 37 = @external_module_declaration
 | 38 = @export_as_namespace_declaration
 | 39 = @global_augmentation_declaration
+| 40 = @using_decl_stmt
 ;
 
-@decl_stmt = @var_decl_stmt | @const_decl_stmt | @let_stmt | @legacy_let_stmt;
+@decl_stmt = @var_decl_stmt | @const_decl_stmt | @let_stmt | @legacy_let_stmt | @using_decl_stmt;
 
 @export_declaration = @export_all_declaration | @export_default_declaration | @export_named_declaration;