Style and Class binding improvements

[CyberAP]

Rendered

Introduce a couple of improvements to Style and Class bindings:

• Secondary argument for direct prop-value bindings

  <input :class:is-active="isActive">

• Modifiers for secondary style arguments

  <input :style:custom-property.prop="customPropertyValue">
  <input :style:width.px="width">

[posva]

This was asked for before at vuejs/vue#4956
Same for implicit prop values vuejs/vue#2877

Given the existing syntax for directives (like v-bind) this introduces a custom attribute named class:property (property being dynamic) and a custom behavior for v-bind, which ironically helps to making things overcomplicated which is your first point in motivation

[CyberAP]

It does not introduce a custom attribute and is a syntax sugar for an existing object configuration for v-bind. That's why it said that users who use render functions won't be affected by this change.