Inappropriate string literal completions in object literals

[DanielRosenwasser]

Found in microsoft/vscode#12667

var foo;

interface I {
    metadata: string;
    wat: string;
}

var x: I = {
    metadata: "/*$*/"
}

Expected: Completions of every identifier in the file, or no completions at all.
Actual: Completions of property names for the containing object literal's apparent type.

[mhegazy]

#11044 seems like another duplicate of this issue

[DanielRosenwasser]

That looks to me like an independent issue. . shouldn't be a completion character in that context, but should in others.