fix($parse): allow for new lines in expr when promise unwrapping is on

Previously, when unwrapping promises was set to `true`,
an error would occur if a parsed expression had a
new line in it.
This was because when generating the `evaledFnGetter` code,
a new line in an parsed expression would create a new line
in a JS string in that code, which is illegal. That is:
```js
pw("A+
B")
```

Closes #4718

src/ng/parse.js

@@ -1017,7 +1017,7 @@ function getterFn(path, options, fullExp) {
                       : '((k&&k.hasOwnProperty("' + key + '"))?k:s)') + '["' + key + '"]' + ';\n' +
               (options.unwrapPromises
                 ? 'if (s && s.then) {\n' +
-                  ' pw("' + fullExp.replace(/\"/g, '\\"') + '");\n' +
+                  ' pw("' + fullExp.replace(/(["\r\n])/g, '\\$1') + '");\n' +
                   ' if (!("$$v" in s)) {\n' +
                     ' p=s;\n' +
                     ' p.$$v = undefined;\n' +