Don't consume 'is' keyword if there is a preceding line terminator

[JsonFreeman]

ASI should kick in when we parse a type predicate, in a case like this:

interface I {
    foo(callback: (a: any, b: any) => void): I
    is(): boolean;
}

This should not be parsed as a type predicate. The grammar production should look something like

Type:
     Identifier [No line terminator here] is Type

[yuit]

lgtm