Escape shortcut fails when first text character is a `:`

```
@if(true) {
    @::Something
}
```

The above code block produces this error: `"::" is not valid at the start of a code block. Only identifiers, keywords, comments, "(" and "{" are valid.`

The expected output is `:Something`. I can get around this by using `<text>:Something</text>`. My assumption is because `::` is a valid namespace qualifier in c#.
