PerspectiveCamera and CinematicCamera: Convert to ES6 class.

[beginor]

• PerspectiveCamera: Convert to ES6 class
• CinematicCamera: Convert to ES6 class

[Mugen87]

Sorry, but CinematicCamera can't be converted since it exists in examples/js.

[beginor]

if CinematicCamera can't be converted to es6, it looks PerspectiveCamera can not be converted to es6 too, Could you please tell me why we can not the classes in examples/js?

[Mugen87]

The example modules are mostly generated from examples/js files. The script which does the conversion does not support classes. Besides, examples/js should also work in older browsers. The following PR needs to solved first before the class conversion can be finalized: #20527