correct handling of escaped quotes

[stoyan]

this confuses the parser:

  .sele {
    content: "he\"lo";
  }

this is ok:

  .sele {
    content: "helo";
  }

{ type: 'property', 
  name: 'content', 
  value: '"helo"' }

[stoyan]

another example is the box model hack

.sele {
  voice-family: "\"}\""; 
  voice-family:inherit;
}

[brettstimmerman]

Ouch. Good catch @stoyan.