Inconsistency: token `dl` not use in most of the language but used in JS

[BenSouchet]

A simple question I haven't found: Why the token dl (Literal String Delimiter) is used in JavaScript but not on others languages (Python, C, C++, PHP,....)

Diff

In JavaScript:

'Hello World!'

<span class="dl">'</span><span class="s1">Hello World!</span><span class="dl">'</span>

In PHP:

'Hello World!'

<span class="s1">'Hello World!'</span>

So is it a bug ? Or is there something I don't know ? Is the dl token deprecated ?