Update acorn-dynamic-import to v4.

Author: goto-bus-stop

build.js

@@ -19,4 +19,3 @@ function compile (name, output) { // eslint-disable-line no-unused-vars
 
 compile('acorn-bigint', './lib/bigint/index.js')
 compile('acorn-import-meta', './lib/import-meta/index.js')
-compile('./lib/dynamic-import/source', './lib/dynamic-import/index.js')

index.js

@@ -4,7 +4,7 @@ var xtend = require('xtend')
 var CJSParser = acorn.Parser
   .extend(require('./lib/bigint'))
 var ESModulesParser = CJSParser
-  .extend(require('./lib/dynamic-import'))
+  .extend(require('acorn-dynamic-import').default)
   .extend(require('./lib/import-meta'))
 
 function mapOptions (opts) {

lib/dynamic-import/index.js

@@ -8,6 +8,7 @@
   },
   "dependencies": {
     "acorn": "^6.0.1",
+    "acorn-dynamic-import": "^4.0.0",
     "acorn-walk": "^6.0.1",
     "xtend": "^4.0.1"
   },

lib/dynamic-import/source.js

@@ -1,6 +1,6 @@
 var xtend = require('xtend')
 var walk = require('acorn-walk')
-var dynamicImportKey = require('./lib/dynamic-import').DynamicImportKey
+var dynamicImportKey = require('acorn-dynamic-import').DynamicImportKey
 
 var base = xtend(walk.base)
 base[dynamicImportKey] = function () {}