New features

• Support for Go 1.12 and synchronous callbacks.
• Introduced HTMLElement.
• Implemented most missing functions and properties for Element.
• Window.Open and SetLocation.
• Separate functions for loading JS and CSS files in require package.

Fixes, tests and gelpers

• Added Chrome-based tests for WebSockets.
• Fix race condition on getting a dial error for WS.
• Added js.Error constructor.