Double doublequotes in here-string scopes as a character.escape

[msftrncs]

Environment

• Editor and Version: VS Code: 1.26.1
• Your primary theme: Monokai Dimmed

Issue Description

Doubled doublequotes in here-string is scoped as a character escape.

Expected Behavior

Doubled doublequotes are not any kind of an escaped character in a here-string.

Code Samples

@"
Hello There
""Doubled DoubleQuotes""
"@

[msftrncs]

Single quote here-string has similar problem, treats double single-quotes as character escape, where there are no valid character escapes in a single-quoted here-string.