idl_parser: Enable "namespace" to be parsed into ASTs

This CL is a 1st step of supporting "namespace" definition in WebIDL.

In order to check if ASTs are made correctly, I made pattern matching tests.

Bug: 727971
Change-Id: I033e9bab2623675f40a9b941cc53cdecef0c186d
Reviewed-on: https://chromium-review.googlesource.com/676692
Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Reviewed-by: Kenichi Ishibashi <bashi@chromium.org>
Commit-Queue: Lisa Suzuki <lisabelle@google.com>
Cr-Original-Commit-Position: refs/heads/master@{#504265}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: fd4acd522e94c696bb6e1d177e354e0ccc53ba1c
3 files changed