fix(view): fix falsy boolean evaluation on comments

[xHeaven]

Problem

When parsing HTML comments, any 0 character (like in URLs such as http://www.w3.org/2000/svg) was being treated as "false" in PHP. This made the lexer stop parsing too early and break up the comment before it was supposed to.

Root Cause

PHP treats the string "0" as false, so when $this->current === '0', the loop condition fails and exits before finding the actual closing -->.

Fix

We just need to be more specific about checking for null instead of relying on PHP's truthiness:

- while ($this->seek(3) !== '-->' && $this->current) {
+ while ($this->seek(3) !== '-->' && $this->current !== null) {

Explicit null check FTW.

Relates to #1288 (failing PR, merge this first)
Fixes #1287

[brendt]

Thanks for fixing my dumb mistakes :D

So we now need to update #1288, I reckon?