JsonReader: Support JSON intermixed with other content

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I have a fairly large HTML page that has several JSON objects & arrays in it. I 
use a PushbackReader to read the file and handle any text I'm interested in 
(and determine when to start a JsonReader read). If I pass my Reader (or any 
reader) to JsonReader, it will read 1024 characters regardless of content. This 
means I may miss some JSON.
i.e. I may miss myObject2 in the following example because it might remain 
unprocessed in the JsonReader buffer.

<h1>some html</h1>
<script language=javascript>
var myObject1={"a":1};
alert("some non-JSON that may or may not exceed the JsonReader buffer size");
var myObject2={"b":2};

NOTE: This is a much simplified version of my problem. The JSON data is 
actually quiet large as is the HTML content.

As a temporary workaround, I've added the following method to JsonReader that 
allows me to push the unprocessed characters in the JsonReader buffer back into 
my PushbackReader (so I can start searching for "var myObject2=").

  public char[] getUnreadCharacters() {
      char[] output = new char[limit - pos];
      if (pos < limit) {
          System.arraycopy(buffer, pos, output, 0, limit - pos);
      }
      return output;
  }

I also added a constructor that allows me to modify the buffer size.

Original issue reported on code.google.com by christia...@gmail.com on 6 Oct 2013 at 3:44