add more browsers to e2e test

[eidng8]

This issue serves as a reminder and meta-issue of all e2e related obstacles. Each issue mentioned here needs their own issue created when tackled in the future.

Currently Chrome is used as the baseline. Other browsers are scarcely tested by hand. There are a few issues blocking automated tests:

• geckodriver reports protocol errors (.moveTo() & doubleClick()).
• edge driver requires selenium-server and needs more configuration which requires elevated command prompt. More trials needs to perform with Travis' Windows environment, which is still in early stage.
• cannot find Chrome binary error occurs on Windows environment.
• function uv_close, file ../deps/uv/src/unix/core.c, line 187. error occurs on OSX, which may be related to webpack@4, node@13, Mac crashes when compiler.watch().close() webpack/webpack#10037.