chore(runtime-core): use getGlobalThis when installing HMR API (#3217)

Author: edison1105

packages/runtime-core/src/hmr.ts

@@ -9,6 +9,7 @@ import {
 } from './component'
 import { queueJob, queuePostFlushCb } from './scheduler'
 import { extend, getGlobalThis } from '@vue/shared'
+import { warn } from './warning'
 
 type HMRComponent = ComponentOptions | ClassComponent