fix formatting for lines that start with continuation of multiline comments

tests/cases/fourslash/formattingWithMultilineComments.ts

@@ -0,0 +1,9 @@
+/// <reference path="fourslash.ts"/>
+
+////f(/*
+/////*2*/         */() => { /*1*/ });
+
+goTo.marker("1");
+edit.insertLine("");
+goTo.marker("2");
+verify.currentLineContentIs("         */() => {");