* lisp/progmodes/ruby-mode.el

* lisp/progmodes/ruby-mode.el
(ruby-syntax-propertize-function): After everything else, search
for expansions in string literals, mark their insides as
whitespace syntax and save match data for font-lock.
(ruby-font-lock-keywords): Highlight just the 2nd group from
expression expansion matches.
(ruby-match-expression-expansion): Use the match data saved to the
text property in ruby-syntax-propertize-function.

* test/automated/ruby-mode-tests.el
Change direct font-lock face references to var references.
(ruby-interpolation-suppresses-syntax-inside): New test.
(ruby-interpolation-inside-percent-literal-with-paren): New
failing test.