Allow escaped dot within class name

Author: plesiecki

src/__tests__/classes.js

@@ -43,3 +43,9 @@ test('ClassName#set value', ".fo\\o", (t, selectors) => {
     className.value = "bar";
     t.deepEqual(className.raws, {});
 });
+
+test('escaped dot in class name', '.foo\\.bar', (t, tree) => {
+    t.deepEqual(tree.nodes[0].nodes[0].type, 'class');
+    t.deepEqual(tree.nodes[0].nodes[0].value, 'foo.bar');
+    t.deepEqual(tree.nodes[0].nodes[0].raws.value, 'foo\\.bar');
+});

src/parser.js

@@ -821,7 +821,7 @@ export default class Parser {
             }
             nextToken = this.nextToken;
         }
-        const hasClass = indexesOf(word, '.');
+        const hasClass = indexesOf(word, '.').filter(i => word[i - 1] !== '\\');
         let hasId = indexesOf(word, '#');
         // Eliminate Sass interpolations from the list of id indexes
         const interpolations = indexesOf(word, '#{');