Fix: allow auto-semicolon insertion before prefix-less decimal literals

[jackschu]

1
.2

was resulting in

program [0, 0] - [2, 0]
  ERROR [0, 0] - [1, 1]
    number [0, 0] - [0, 1]
  expression_statement [1, 1] - [1, 2]
    number [1, 1] - [1, 2]

Because auto-semi-insertion was not allowed before .