fix: build config

Author: QingWei-Li

Diff for: build/build-ssr.js

@@ -9,7 +9,8 @@ rollup
     plugins: [
       async(),
       replace({
-        __VERSION__: process.env.VERSION || require('../package.json').version
+        __VERSION__: process.env.VERSION || require('../package.json').version,
+        'process.env.SSR': true
       }),
       buble({
         transforms: {

Diff for: build/build.js

@@ -18,7 +18,8 @@ var build = function (opts) {
         commonjs(),
         nodeResolve(),
         replace({
-          __VERSION__: version
+          __VERSION__: version,
+          'process.env.SSR': false
         })
       ])
     })