Remove dart generator code from json schema compiler.

tools/json_schema_compiler/dart_test/events.idl

-// Copyright 2013 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// This comment is for the events namespace.
-namespace events {
-  dictionary EventArgumentElement {
-    DOMString elementStringArg;
-  };
-
-  dictionary EventArgument {
-    // A file entry
-    [instanceOf=FileEntry] object entryArg;
-
-    // A string
-    DOMString stringArg;
-
-    // A primitive
-    int intArg;
-
-    // An array
-    EventArgumentElement[] elements;
-
-    // Optional file entry
-    [instanceOf=FileEntry] object? optionalEntryArg;
-
-    // A string
-    DOMString? optionalStringArg;
-
-    // A primitive
-    int? optionalIntArg;
-
-    // An array
-    EventArgumentElement[]? optionalElements;
-  };
-
-  interface Events {
-    // Documentation for the first basic event.
-    static void firstBasicEvent();
-
-    // Documentation for the second basic event.
-    static void secondBasicEvent();
-
-    // Documentation for an event with a non-optional primitive argument.
-    static void nonOptionalPrimitiveArgEvent(int argument);
-
-    // Documentation for an event with an optional primitive argument.
-    static void optionalPrimitiveArgEvent(optional int argument);
-
-    // Documentation for an event with a non-optional dictionary argument.
-    static void nonOptionalDictArgEvent(EventArgument argument);
-
-    // Documentation for an event with a optional dictionary argument.
-    static void optionalDictArgEvent(EventArgument argument);
-  };
-};