Limit QuickView to literal color names in some languages

For #6836.
Limits QuickView to only literal color names in JS (including JSON), PHP and CoffeeScript.
Includes Unit tests and one new test file.
Drive-by comment: "checkForLiteral()" is a name that leaves things vague about what's returned.  Maybe something like "isNamedColor()"?

Similarly for "literalCheck" -- how about "disallowNamedColors" or "ignoreNamedColors"?