perf: replace startsWith with strict equality (#308)

Author: btea

src/parser.js

@@ -581,7 +581,7 @@ export default class Parser {
             if (space.endsWith(' ') && rawSpace.endsWith(' ')) {
                 spaces.before = space.slice(0, space.length - 1);
                 raws.spaces.before = rawSpace.slice(0, rawSpace.length - 1);
-            } else if (space.startsWith(' ') && rawSpace.startsWith(' ')) {
+            } else if (space[0] === ' ' && rawSpace[0] === ' ') {
                 spaces.after = space.slice(1);
                 raws.spaces.after = rawSpace.slice(1);
             } else {