Adding support for SCSS and Sass files.

testdata/expected/file.sass

@@ -0,0 +1,22 @@
+/**
+ * Copyright 2018 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+$font-stack:    Helvetica, sans-serif
+$primary-color: #333
+
+body
+  font: 100% $font-stack
+  color: $primary-color

testdata/expected/file.scss

@@ -0,0 +1,22 @@
+/**
+ * Copyright 2018 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+.div {
+    color: red;
+    .child{
+        color: green;
+    }
+}

testdata/initial/file.sass

@@ -0,0 +1,6 @@
+$font-stack:    Helvetica, sans-serif
+$primary-color: #333
+
+body
+  font: 100% $font-stack
+  color: $primary-color

testdata/initial/file.scss

@@ -0,0 +1,6 @@
+.div {
+    color: red;
+    .child{
+        color: green;
+    }
+}