allowing @properties to be referenced in naked interpolations

test/test_string_interpolation.coffee

@@ -40,3 +40,9 @@ ok "${hello + ' ' + world + '!'}" is 'Hello World!'
 list: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
 ok "values: ${list.join(', ')}, length: ${list.length}." is 'values: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, length: 10.'
 ok "values: ${list.join ' '}" is 'values: 0 1 2 3 4 5 6 7 8 9'
+
+obj: {
+  name: 'Joe'
+  hi: -> "Hello $@name."
+}
+ok obj.hi() is "Hello Joe."