feat(devtools): store functional render context on vnode in development (vuejs#8586)

Author: znck

src/core/vdom/create-functional-component.js

@@ -105,24 +105,27 @@ export function createFunctionalComponent (
   const vnode = options.render.call(null, renderContext._c, renderContext)
 
   if (vnode instanceof VNode) {
-    return cloneAndMarkFunctionalResult(vnode, data, renderContext.parent, options)
+    return cloneAndMarkFunctionalResult(vnode, data, renderContext.parent, options, renderContext)
   } else if (Array.isArray(vnode)) {
     const vnodes = normalizeChildren(vnode) || []
     const res = new Array(vnodes.length)
     for (let i = 0; i < vnodes.length; i++) {
-      res[i] = cloneAndMarkFunctionalResult(vnodes[i], data, renderContext.parent, options)
+      res[i] = cloneAndMarkFunctionalResult(vnodes[i], data, renderContext.parent, options, renderContext)
     }
     return res
   }
 }
 
-function cloneAndMarkFunctionalResult (vnode, data, contextVm, options) {
+function cloneAndMarkFunctionalResult (vnode, data, contextVm, options, renderContext) {
   // #7817 clone node before setting fnContext, otherwise if the node is reused
   // (e.g. it was from a cached normal slot) the fnContext causes named slots
   // that should not be matched to match.
   const clone = cloneVNode(vnode)
   clone.fnContext = contextVm
   clone.fnOptions = options
+  if (process.env.NODE_ENV !== 'production') {
+    ;(clone.devtoolsMeta = clone.devtoolsMeta || {}).renderContext = renderContext
+  }
   if (data.slot) {
     (clone.data || (clone.data = {})).slot = data.slot
   }

src/core/vdom/vnode.js

@@ -26,6 +26,7 @@ export default class VNode {
   ssrContext: Object | void;
   fnContext: Component | void; // real context vm for functional nodes
   fnOptions: ?ComponentOptions; // for SSR caching
+  devtoolsMeta: ?Object; // used to store functional render context for devtools
   fnScopeId: ?string; // functional scope id support
 
   constructor (