[color picker] RGB value can be manually typed out and it can go above 255

[weiseng18]

Current behaviour is typing in a number larger than 255 will cause the value of that color type to be read as 255.

rgb(10, 1000, 10) = rgb(10, 255, 10)

Solutions:

• alert user when input contains an number larger than 255
• ignore change if number is larger than 255

Other features:

• add cap to number of characters (3), so that user will not be able to type/paste more than 3 digits

[weiseng18]

selectionStart and selectionEnd properties do not work for <input> with type number. It seems that it is not feasible to detect a selection for <input> with type number

As <input type="number"> is a basic HTML element, this is actually HTML standard behaviour