Support non-trivial SASS media selectors (#11455)

This change adds support for media selectors with a query that consist
of more than just a single word.

Change-Id: Id6a09de8e88984ad052321ae93ffa2e7c2ba1c04
Merge commit 'a52ceb96590333' into 7.1

Conflicts:
	theme-compiler/src/com/vaadin/sass/internal/parser/Parser.java

Change-Id: I049a08a5d129b8072bf91554ca0eab0d44e537e3