Fix ScssTemplate#sass_options when using sass-embedded

Add a test for SassTemplate with unsupported options.

lib/tilt/sass.rb

@@ -70,9 +70,9 @@ class ScssTemplate < SassTemplate
     private
 
     def sass_options
-      super
-      @options[:syntax] = :scss
-      @options
+      opts = super
+      opts[:syntax] = :scss
+      opts
     end
   end
 end

test/tilt_sasstemplate_test.rb

@@ -9,21 +9,26 @@
     assert_equal false, Tilt::SassTemplate.new{''}.metadata[:allows_script]
   end
 
-  it "compiles and evaluates the template on #render" do
+  it "compiles and evaluates the sass template on #render" do
     template = Tilt::SassTemplate.new({ style: :compressed }) { |t| "#main\n  background-color: #0000f1" }
     3.times { assert_equal "#main{background-color:#0000f1}", template.render.chomp }
   end
 
+  it "compiles and evaluates the sass template on #render with unsupported options" do
+    template = Tilt::SassTemplate.new({ style: :compressed, outvar: '@a' }) { |t| "#main\n  background-color: #0000f1" }
+    3.times { assert_equal "#main{background-color:#0000f1}", template.render.chomp }
+  end
+
   it "is registered for '.scss' files" do
     assert_equal Tilt::ScssTemplate, Tilt['test.scss']
   end
 
-  it "compiles and evaluates the template on #render" do
+  it "compiles and evaluates the scss template on #render" do
     template = Tilt::ScssTemplate.new({ style: :compressed }) { |t| "#main {\n  background-color: #0000f1;\n}" }
     3.times { assert_equal "#main{background-color:#0000f1}", template.render.chomp }
   end
 
-  it "compiles and evaluates the template on #render with unsupported options" do
+  it "compiles and evaluates the scss template on #render with unsupported options" do
     template = Tilt::ScssTemplate.new({ style: :compressed, outvar: '@a' }) { |t| "#main {\n  background-color: #0000f1;\n}" }
     3.times { assert_equal "#main{background-color:#0000f1}", template.render.chomp }
   end