fix: avoid accidentally trigerring the installedBrowsers getter

fixes vuejs#5286

Author: haoqunjiang

packages/@vue/cli-shared-utils/index.js

@@ -19,3 +19,10 @@
 exports.chalk = require('chalk')
 exports.execa = require('execa')
 exports.semver = require('semver')
+
+Object.defineProperty(exports, 'installedBrowsers', {
+  enumerable: true,
+  get () {
+    return exports.getInstalledBrowsers()
+  }
+})

packages/@vue/cli-shared-utils/lib/env.js

@@ -178,44 +178,41 @@ function getMacAppVersion (bundleIdentifier) {
   }
 }
 
-Object.defineProperty(exports, 'installedBrowsers', {
-  enumerable: true,
-  get () {
-    if (hasCheckedBrowsers) {
-      return browsers
-    }
-    hasCheckedBrowsers = true
-
-    if (exports.isLinux) {
-      browsers.chrome = getLinuxAppVersion('google-chrome')
-      browsers.firefox = getLinuxAppVersion('firefox')
-    } else if (exports.isMacintosh) {
-      browsers.chrome = getMacAppVersion('com.google.Chrome')
-      browsers.firefox = getMacAppVersion('org.mozilla.firefox')
-    } else if (exports.isWindows) {
-      // get chrome stable version
-      // https://stackoverflow.com/a/51773107/2302258
-      const chromeQueryResult = tryRun(
-        'reg query "HKLM\\Software\\Google\\Update\\Clients\\{8A69D345-D564-463c-AFF1-A69D9E530F96}" /v pv /reg:32'
-      ) || tryRun(
-        'reg query "HKCU\\Software\\Google\\Update\\Clients\\{8A69D345-D564-463c-AFF1-A69D9E530F96}" /v pv /reg:32'
-      )
-      if (chromeQueryResult) {
-        const matched = chromeQueryResult.match(/REG_SZ\s+(\S*)$/)
-        browsers.chrome = matched && matched[1]
-      }
-
-      // get firefox version
-      // https://community.spiceworks.com/topic/111518-how-to-determine-version-of-installed-firefox-in-windows-batchscript
-      const ffQueryResult = tryRun(
-        'reg query "HKLM\\Software\\Mozilla\\Mozilla Firefox" /v CurrentVersion'
-      )
-      if (ffQueryResult) {
-        const matched = ffQueryResult.match(/REG_SZ\s+(\S*)$/)
-        browsers.firefox = matched && matched[1]
-      }
+exports.getInstalledBrowsers = () => {
+  if (hasCheckedBrowsers) {
+    return browsers
+  }
+  hasCheckedBrowsers = true
+
+  if (exports.isLinux) {
+    browsers.chrome = getLinuxAppVersion('google-chrome')
+    browsers.firefox = getLinuxAppVersion('firefox')
+  } else if (exports.isMacintosh) {
+    browsers.chrome = getMacAppVersion('com.google.Chrome')
+    browsers.firefox = getMacAppVersion('org.mozilla.firefox')
+  } else if (exports.isWindows) {
+    // get chrome stable version
+    // https://stackoverflow.com/a/51773107/2302258
+    const chromeQueryResult = tryRun(
+      'reg query "HKLM\\Software\\Google\\Update\\Clients\\{8A69D345-D564-463c-AFF1-A69D9E530F96}" /v pv /reg:32'
+    ) || tryRun(
+      'reg query "HKCU\\Software\\Google\\Update\\Clients\\{8A69D345-D564-463c-AFF1-A69D9E530F96}" /v pv /reg:32'
+    )
+    if (chromeQueryResult) {
+      const matched = chromeQueryResult.match(/REG_SZ\s+(\S*)$/)
+      browsers.chrome = matched && matched[1]
     }
 
-    return browsers
+    // get firefox version
+    // https://community.spiceworks.com/topic/111518-how-to-determine-version-of-installed-firefox-in-windows-batchscript
+    const ffQueryResult = tryRun(
+      'reg query "HKLM\\Software\\Mozilla\\Mozilla Firefox" /v CurrentVersion'
+    )
+    if (ffQueryResult) {
+      const matched = ffQueryResult.match(/REG_SZ\s+(\S*)$/)
+      browsers.firefox = matched && matched[1]
+    }
   }
-})
+
+  return browsers
+}