Fixes microsoft/monaco-editor#1729: Fix running the build on Windows …

…(files with \r\n)

build/gulpfile.editor.js

@@ -197,7 +197,7 @@ const compileEditorESMTask = task.define('compile-editor-esm', () => {
 });
 
 function toExternalDTS(contents) {
-	let lines = contents.split('\n');
+	let lines = contents.split(/\r\n|\r|\n/);
 	let killNextCloseCurlyBrace = false;
 	for (let i = 0; i < lines.length; i++) {
 		let line = lines[i];