Syntax highlighting of `'"'` is incorrect

[carols10cents]

To reproduce:

// what should happen
struct SyntaxHighlightingWorks {
    field: i32,
}

const MYCHARS: &'static [char] = &['"'];

// what shouldn't happen
struct SyntaxHighlightingBroken {
    field: i32,
}

The second struct definition should be highlighted in the same way as the first struct definition is rather than behaving as an unclosed string literal.

Screenshot of the undesired behavior:

[rtsuk]

@reitermarkus does this look easy to fix? I've not gotten into the syntax stuff yet.