A shortcoming of grammar color displaying in typescript

[BirdLeeSCUT]

• VSCode Version: 1.7.2
• OS Version: Windows 10 x64

Steps to Reproduce:
There is a shortcoming of grammar color displaying in typescript, as follow:

 interface Itest {
	a: 'a1' // a1 is good
		| 'a2' // a2 is good
		| 'a3' // a3 is good
	b: {
		a: 'a1'
			| 'a2' // oh , the color is not good !
			| 'a3' // oh , the color is not good !
	}
}

Sometimes we want to give clear indication of the meanings of every items of String Literal Types in inline comment, so we would break String Literal Types into many lines.

[mjbvz]

This issue was moved to microsoft/TypeScript-TmLanguage#376