Fix test about assigning to frozen object in chrome.
Fix test about assigning to frozen object in chrome.

shupan123/vue-fixed-type,th0r/vue,fergaldoyle/vue,fergaldoyle/vue,th0r/vue,shupan123/vue-fixed-type,diermengdierme/vue,th0r/vue,shupan123/vue-fixed-type,fergaldoyle/vue,diermengdierme/vue,diermengdierme/vue