Comments are in some cases highlighted incorrectly

Consider the following two similar Solidity contracts:
```
contract MetaCoin {
constructor() {
balances[tx.origin/***stuff***/] = 10000;
}
}
```
and
```
contract MetaCoin2 {
constructor() {
balances[tx.origin /***stuff***/] = 10000;
}
}
```
In the first case, highlightjs-solidity seems to parse the `/` after `tx.origin` as division and the `*` as operators. In `MetaCoin2`, it will correctly parse the comment (when there is a space between `tx.origin` and `/`).