add production tips info

src/entries/web-runtime.js

@@ -37,6 +37,15 @@ Vue.prototype.$mount = function (
   return this._mount(el, hydrating)
 }
 
+if (process.env.NODE_ENV !== 'production' &&
+    inBrowser && typeof console !== 'undefined') {
+  console[console.info ? 'info' : 'log'](
+    `You are running Vue in development mode.\n` +
+    `Make sure to turn on production mode when deploying for production.\n` +
+    `See more tips at https://vuejs.org/guide/deployment.html`
+  )
+}
+
 // devtools global hook
 /* istanbul ignore next */
 setTimeout(() => {
@@ -47,8 +56,8 @@ setTimeout(() => {
       process.env.NODE_ENV !== 'production' &&
       inBrowser && !isEdge && /Chrome\/\d+/.test(window.navigator.userAgent)
     ) {
-      console.log(
-        'Download the Vue Devtools for a better development experience:\n' +
+      console[console.info ? 'info' : 'log'](
+        'Download the Vue Devtools extension for a better development experience:\n' +
         'https://github.com/vuejs/vue-devtools'
       )
     }

test/helpers/to-have-been-warned.js

@@ -1,10 +1,15 @@
+function noop () {}
+
 if (typeof console === 'undefined') {
   window.console = {
-    warn: function () {},
-    error: function () {}
+    warn: noop,
+    error: noop
   }
 }
 
+// avoid info messages during test
+console.info = noop
+
 let asserted
 function hasWarned (msg) {
   var count = console.error.calls.count()