remove utf8 BOM from start of files

src/lexer.rs

@@ -40,7 +40,7 @@ impl<'a> Iterator for Lexer<'a> {
 impl<'a> Lexer<'a> {
     pub fn new(file: &'a Arc<File>) -> Lexer<'a> {
         Lexer {
-            buf: file.source().chars().peekable(),
+            buf: file.source().trim_start_matches("\u{ef}\u{bb}\u{bf}").trim_start_matches("\u{feff}").chars().peekable(),
             pos: 0,
             file,
         }

tests/misc.rs

@@ -96,3 +96,13 @@ test!(
     "a {\n  a: b\n}\n\nb {}\n",
     "a {\n  a: b;\n}\n"
 );
+test!(
+    file_begins_with_utf8_bom,
+    "\u{feff}a {\n  color: red\n}\n",
+    "a {\n  color: red;\n}\n"
+);
+test!(
+    file_begins_with_bom,
+    "\u{ef}\u{bb}\u{bf}a {\n  color: red\n}\n",
+    "a {\n  color: red;\n}\n"
+);