allow multiline expression on v_model

[wangmeng1991]

Version

3.0.1

Reproduction link

https://jsbin.com/susulujace/edit?html,output
template compiler

Steps to reproduce

Check the console

What is expected?

allow multiline expression on v_model

What is actually happening?

runner-4.1.8.min.js:1 [Vue warn]: Template compilation error: v-model value must be a valid JavaScript member expression.
1  |  <input v-model="
   |                  ^
2  |                                      toolbar
   |  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
3  |                                .model
   |  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
4  |                                    ">{{model}}
   |  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
  at <App>