Storing strings with SERIALIZED_MARKER at the beginning fails

[jviereck]

Assuming a developer wants to store the string:

str = "'__lfsc__:hello world";

in localForage/WebSQL driver, the string can be saved BUT it cannot be read out. This is, as the marker makes the WebSQL driver think the content is serialized and tries to pass hello world to the JSON.parse(...) method - which fails.

An easy fix is to prefix all strings stored in the WebSQL driver and not just the ones that serialized:

// Marker used here:
//   s: ^= String
//   o: ^= Object
localforage.setItem('foo') // -> gets stored as "s:foo" << string
localforage.setItem({hello: "world"}) // -> gets stored as 'o:{"hello":"world"}'