Index: node_modules/postcss/lib/fromJSON.js
===================================================================
--- node_modules/postcss/lib/fromJSON.js	(revision 2058e5c694bb6097866a5fe6503c519e8f74970f)
+++ node_modules/postcss/lib/fromJSON.js	(revision 2058e5c694bb6097866a5fe6503c519e8f74970f)
@@ -0,0 +1,54 @@
+'use strict'
+
+let AtRule = require('./at-rule')
+let Comment = require('./comment')
+let Declaration = require('./declaration')
+let Input = require('./input')
+let PreviousMap = require('./previous-map')
+let Root = require('./root')
+let Rule = require('./rule')
+
+function fromJSON(json, inputs) {
+  if (Array.isArray(json)) return json.map(n => fromJSON(n))
+
+  let { inputs: ownInputs, ...defaults } = json
+  if (ownInputs) {
+    inputs = []
+    for (let input of ownInputs) {
+      let inputHydrated = { ...input, __proto__: Input.prototype }
+      if (inputHydrated.map) {
+        inputHydrated.map = {
+          ...inputHydrated.map,
+          __proto__: PreviousMap.prototype
+        }
+      }
+      inputs.push(inputHydrated)
+    }
+  }
+  if (defaults.nodes) {
+    defaults.nodes = json.nodes.map(n => fromJSON(n, inputs))
+  }
+  if (defaults.source) {
+    let { inputId, ...source } = defaults.source
+    defaults.source = source
+    if (inputId != null) {
+      defaults.source.input = inputs[inputId]
+    }
+  }
+  if (defaults.type === 'root') {
+    return new Root(defaults)
+  } else if (defaults.type === 'decl') {
+    return new Declaration(defaults)
+  } else if (defaults.type === 'rule') {
+    return new Rule(defaults)
+  } else if (defaults.type === 'comment') {
+    return new Comment(defaults)
+  } else if (defaults.type === 'atrule') {
+    return new AtRule(defaults)
+  } else {
+    throw new Error('Unknown node type: ' + json.type)
+  }
+}
+
+module.exports = fromJSON
+fromJSON.default = fromJSON