Why doesn't the DART language use a special character to identify variables?

Question

I come from a PHP background and I have been considering looking at DART in more detail.

DART is an, open source, front-end/back-end, language for web development.

PHP has a special $ (dollar) character to indicate variables:

$variable
CONSTANT
'string'
"etc"

I find that dollar sign to be really useful for speeding up the proces of refactoring, especially if PHP code is mixed with HTML or content. It reduces the number of false positives when, say, doing a find and replace.

As DART is a completely fresh language (with no legacy) that can be embedded in HTML, it surprised me to see that it does not have any special identifier to indicate variables.

What's the reasoning behind that design decision?