For destructuring bind, the parser needs to complain about things
which are inappropriate to have on the left-hand side.

Previously, regexp literals and template literals were let through
the parser inappropriately. This patch turns those into errors.

This patch also fixes off-by-one errors in reporting the location
of this type of error for strings and numbers. Before the patch,
the error would look like:

d8> var {x: 3} = {x: 4}
(d8):1: SyntaxError: Unexpected number
var {x: 3} = {x: 4}
      ^
SyntaxError: Unexpected number

And with the patch, the error is

d8> var {x: 3} = {x: 4}
(d8):1: SyntaxError: Unexpected number
var {x: 3} = {x: 4}
        ^
SyntaxError: Unexpected number

R=rossberg

Review URL: https://codereview.chromium.org/1236803003

Cr-Commit-Position: refs/heads/master@{#29661}