replaced let with const

lib/single-file/css-declarations-parser.js

@@ -615,7 +615,7 @@ this.parseCss = this.parseCss || (() => {
 				const temp = [s.token];
 				while (!(s.next().tokenType == SEMICOLON_TOKEN_TYPE || s.next().tokenType == EOF_TOKEN_TYPE))
 					temp.push(consumeAComponentValue(s));
-				let decl = consumeADeclaration(new TokenStream(temp));
+				const decl = consumeADeclaration(new TokenStream(temp));
 				if (decl) decls.push(decl);
 			} else {
 				parseerror(s);